Teerawat Issariyakul

[Book Review] The Phantom of the Opera by Gaston Leroux

2012-01-30T05:35:00.001-07:00

Rating: 3/5

Genre: Novel

Book Review

Most of us probably heard of “The Phantom of the Operas”. It is reproduced over and over again in various form. I first saw it in the broadway musical produced by Andrew Loyd Webber. Then I saw it again, when hollywood made it in the movie form. And, this is my third time. This time is in book, audiobook.

As in other novel, the book is more elaborated. It contains a lot of details which is left out by musicals or movies. Also some parts, some important parts, are quite different from the musical and movie production. It is interesting. But I find it quite difficult to follow (esp. for non-native speaker), because it contains so many Theatrical terminology. But it was alright. On the average, I enjoyed it.

I’ve got the audiobook copy narrated by Barrett Whitener. At the beginning, it sounds a bit dull and uninteresting. But I get used to it pretty soon. He made sounds for male and female. It's pretty funny at the beginning. But again, I get used to it pretty soon.

Table of Contents (and the chapter marks on the audiobook version)

Prologue
Chapter I: Is it the Ghost? (11.50)
Chapter II: The New Margarita (32.35)
Chapter III: The Mysterious Reason (54.20)
Chapter IV: Box Five (1.11.00)
Chapter V: The Enchanted Violin (1.39.40)
Chapter VI: A Visit to Box Five (2.17.05)
Chapter VII: Faust and What Followed (2.23.15)
Chapter VIII: The Mysterious Brougham (2.52.16)
Chapter IX: At the Masked Ball (3.09.30)
Chapter X: Forget the Name of the Man's Voice (3.31.45)
Chapter XI: Above the Trap-Doors (3.42.58)
Chapter XII: Apollo's Lyre (4.00.00)
Chapter XIII: A Master-Stroke of the Trap-Door Lover (4.46.39)
Chapter XIV: The Singular Attitude of a Safety-Pin (5.09.50)
Chapter XV: Christine! Christine! (5.22.10)
Chapter XVI: Mme. Giry's Astounding Revelations as to Her Personal Relations with the Opera Ghost??? (5.30.42)
Chapter XVII: The Safety-Pin Again (5.54.01)
Chapter XVIII: The Commissary, The Viscount and the Persian (6.06.45)
Chapter XIX: The Viscount and the Persian (6.17.41)
Chapter XX: In the Cellars of the Opera (6.30.47)
Chapter XXI: Interesting and Instructive Vicissitudes of a Persian in the Cellars of the Opera (7.02.05)
Chapter XXII: In the Torture Chamber (7.31.41)
Chapter XXIII: The Tortures Begin (7.46.51)
Chapter XXIV: Barrels!...Barrels!...Any Barrels to Sell?" (8.00.45)
Chapter XXV: The Scorpion or the Grasshopper: Which? (8.24.02)
Chapter XXVI: The End of the Ghost's Love Story (8.40.27)
Epilogue: The Paris Opera House (9.01.55)

---------------------------------------------------------------------------------------------------------

Book or Audiobooks?

Personally, I prefer audiobooks. It's fun, and I can listen when I'm doing something else. It also makes other activities (e.g., jogging) a lot more fun. For more detail about audiobooks, please read [this post].

About the summary: It takes time to finish up a book. And, when you do, sometimes, you want to review what you learn from the book. If you do not make notes as you read, you might have to go through the book once again. This can be time-consuming when you are dealing with a book. But you can still flip through the book and locate what you are looking for.

However, when the material is an audiobook, it is extremely hard to locate a specific part of content. Most likely you will have to listen to the entire audiobook once again.

This book summary will help solve the pain of having to go through the book all over again.

I am leaving out the details of the books. Most books have interesting examples and case studies, not included here. Reading the original book would be much more entertaining and enlightening. If you like the summary, you may want to get the original from the source below.

In Year 2021

2011-11-05T12:44:00.001-06:00

Remember, a Day Made Of Glass? It's the vision of Corning, a company which manufactures specialty glass and ceramics.

This time it's Microsoft. Let's see Microsoft's vision for year 2021.

Well, at least cars still run on tire...

I have one favor to ask. Talk to me. Tell me which technology is your favorite :)

If you are interested in Corning's video, here it is:

[Book Review] Too Good to Leave, Too Bad to Stay by Mira Kirshenbaum

2011-10-17T07:49:00.000-06:00

Rating: 3.5/5

Genre: Non-fiction

Book Review

Do you know the term “Relationship ambivalence”? It is a state where you feel that your relationship is too good to leave, and, at the same time, you also feel that your relationship is too bad to stay. You feel like screwed up if you make either of the choices. So you don’t decide. You leave it to fate. You wait for the sign to tell you what to do. It may take months, years, or even decades for that sign to come. When the sign came, you’d ask yourself, why did’t I see this coming?, why have I waited for so long?,...

On the other hand, if might find the sign which convince you that your relation ship is too good to leave. And again, when the sign comes, you'd ask yourself, why have I had to live with uneasy feeling, when the only problems in my relationship are so little and trivial and there is nothing fundamentally wrong with my relationship.

One of the reasons is that we tend to use balance scale to weigh pros and cons and then make decision. The problem is that pros and cons are constantly moving and very subjective. You’d feel like you need forever to make the decision. This book, on the other hand, takes the doctor approach. It’s like when you go to see a doctor. The doctor asks you diagnosis questions, and tell you what’s wrong with you (e.g., fever, migraine). This book contains 34 diagnosis questions, that will help you understand whether your relationship is too good to leave or too bad to stay. At the end of the book, the authors provides you with further recommended reading for either of your choice. So you might not just find a way of your relationship ambivalence, but you might also know what to do after you make such the decision.

I found this book, when my relationship is kind of iffy. I'm not sure if I found my answer by reading this book. But my relationship got better before I finish the reading. It could be because of the book. But it could also be because the relationship got better by itself. Anyway, I continued reading to the end of the book.

Overall, I found this book useful and interesting. It contains a lot of case studies, which make the book even more interesting. But it wasn’t that gripping. It’s not the book that I can’t put it down and have to keep on reading.

The Audiobook version of this book is narrated by Adriane McNeely. Her narration is nice, but again not to the degree that keep me so engaged that I can’t put it down. So on the average, this book is ok. It is a fine book and worth listening.

One last nice thing about this book is that all chapters are named after song titles. For example, "All the things you are" (Chapter10) is a song from the musical "Very Warm for May". "If Ever I Should Leave You" (Chapter13) is a song from the musical "Camelot". I find this little things pretty nice and interesting.

Takeaways

Relationship ambivalence makes you feel both too good to leave and too bad to stay at the same time. Avoid it. It’s just a waste of time and spiritual energy.
Balance scale approach is not good for every scenario in life, and definitely not for resolving relationship ambivalence. Doctor approach which asks diagnostic questions seem to work better.

Table of Contents

I. The Problem

Chapter 1. Is You Is or Is you Ain’t My Baby?
Chapter 2. Dancing in the Dark
Issue: Relationship Ambivalence

II: Solution

Chapter 3. Enough Is Enough
Issue: Danger Signs
Chapter 4. It’s Too Late, Baby
Issue: If You’ve Already Decided to Leave
Chapter 5. Let’s Do It, Let’s Fall in Love
Issue: Preconditions for Love
Chapter 6. You’ve Got a Hold on Me
Issue: Power--When the Other Person Is Bossy,
Controlling, Domineering, Overwhelming, ...
Chapter 7. Talk to Me
Issue: Communication
Chapter 8. What Is This Thing Called Love?
Issue: Is There Real Love Left?
Chapter 9. It Don’t Mean a Thing If It Ain’t Got That Swing
Issue: Sex and Physical Affection
Chapter 10. All the Things You Are
Issue: You Partner’s Problems
Chapter 11. Let’s Call the Whole Thing Off
Issue: Personal Bottom Lines
Chapter 12. You Say “Tomayto,” I Say “Tomahto”
Issue: Post-relationship Options
Chapter 13. If Ever I Should Leave You
Issue: Post-relationship Options
Chapter 14. R-E-S-P-E-C-T
Issue: Do You Respect Each Other?
Chapter 15. Who’s Sorry Now?
Issue: Hurts and Betrayals
Chapter 16. I Can’t Get No Satisfaction
Issue: Getting Your Needs Met
Chapter 17. Love to Love You, Baby
Issue: Intimacy--How It Feels to Be Close
Chapter 18. I’ve Got You Under My Skin
Issue: Feeling You Belong Together
Chapter 19. Next Step

Quotes

“What had happened to the sweet woman he’d married? Now, three years later, Steve felt that Lynn had turned into someone who did nothing but complain. Then one Friday coming home from work Steve heard a song on the radio—“When a Man Loves a Woman.” Something about it got through to him, something about his having a responsibility to make sure she knew he loved her. They’d gotten so polarized, he saw, that he’d overlooked the possibility that she was unloving because he was unloving.”
“You can often fix what was broken, but you can rarely fix what’s never work at the first place.”
“The mere talent for power doesn’t make you the kind of power person that destroys relationships. But when the talent controls you and makes you its servant, then you and everyone around you are in big trouble.”
“the real problem in relationships isn’t how untalented we are at bridging our differences; it’s how incredibly talented we are at manufacturing differences out of nothing if necessary, just to create a sense of differentiation, uniqueness, specialness. Besides, communication is the one thing in the universe specifically designed to bridge the gap between our differences. If we’re having trouble with that bridge, partly it’s because we’re so interested in magnifying those differences. But communication is the solution, not the problem.”
“communication is a process of getting naked. Not physically, but interpersonally. The closer you are to someone, the closer communication brings you to this interpersonal nakedness. And love is the place where it’s safe to be naked. ”
“The bottom line is the end of the line....You didn’t invent your bottom line, you discovered it.”
“Perhaps what seems like a “difference” problem is really a communication problem.”
“Somehow, somewhere, when you look deep in your partner’s eyes you’ve got to be able to see yourself.”
“Respect is the soil out of which self-esteem grows. But the fighting and familiarity of relationships is the soil out of which disrespect grows.”
“Time heals all healable wounds.”

---------------------------------------------------------------------------------------------------------

Book or Audiobooks?

2011-09-15T07:58:00.001-06:00

Google Map/Google Earth

The day Google Earth came out, the whole world was stunned. It's the first time we see the useful (and dangerous) civilian application. Starting from seeing the world, we can zoom in and see countries, districts, villages, and houses (including yours).

This is what you see
when you turn on Google Earth

This is What you see
When you look for a city

Nokia Map 3D

I just heard from the show Windows Weekly that Nokia has a pretty awesome map as well. I wasn't very excited. But I might as well check it out. And, again, I was stunned. Here is what I saw:

This is what you see
when you first visited Nokia 3D Map

This is what you see
when you look for a city

I was quite amazed. It's like in a video game or animation. Except it's real!! Check it out. Here is the [ link ]

What about Earth View in Google Map
I did not know that this option exists. But I thought Google must have something similar. And there is. It's called "Earth View". But I was not impressed by Earth View. Nokia map 3D is far better. Well you can see a screenshot here.

Earth View of Google Maps

[Book-Thai] Facebook คืออะไร? ทำไม Facebook จึงประสพความสำเร็จ

2011-06-06T22:59:00.000-06:00

“We’re utility. We’re trying to increase the efficiency to which people can understand their world. We’re not trying to maximize the time spent on our site. We’re trying to help people have a good experience and get the maximum amount out of that time.”--Mark Zuckerberg

ตัวตนของเราออนไลน์

จุดเด่นของ Facebook คือการใช้ตัวตนจริงๆของเรา อันนี้ก็ต่างจาก Social Network Services อื่นๆก่อนหน้านี้ซึ่งคนมักจะสร้างนามแฝงขึ้นมาใช้แทนตัวเอง อันนี้ไม่ได้หมายความว่าเราไม่สามารถใช้นามแฝงในการสร้าง Facebook Account แต่เนื่องจาก Facebook ถูกสร้างขึ้นมาเพื่อพัฒนาการสื่อสารระหว่างคนที่เรารู้จัก การใช้นามแฝงจะทำให้เราได้ประโยขน์จาก Facebook น้อยมาก

ตัวอย่างง่ายๆคือ ในสังคม Facebook เรามักจะยอมรับคนๆนึงเป็นเพื่อน ถ้าเรารู้จักเขาอยู่แล้ว หรือเขาเป็นเพื่อนของเพเพื่อนเรา (ซึ่งเราสามารถดูได้จากรายชื่อเพื่อน ในหน้า profile ของเพื่อนเรา) ถ้ามีคนที่ใช้นามแฝงเข้าไป เพื่อนๆอาจจะไม่รู้จักเขา และไม่รับเขาเป็นเพื่อนใน Facebook ก็ได้

Personal Web Portal

Portal หมายถึงประตู ส่วน Web Portal ก็หมายถึงประตูที่จะนำไปสู่โลกของอินเทอร์เน้ต Web Portal มักถูกใช้โดยผู้ให้บริการอินเทอร์เน็ต เพื่อแสดงข้อมูลต่างๆ ที่สอดคล้องกับความสนใจของผู้ใช้งาน เช่นการสมัครบริการ Terms of Service ค่าบริการ

Personal Web Portal คือ Web Portal ที่สอดคล้องกับความต้องการของผู้ใช้คนหนึ่ง อันนีี้ต้องระบุให้ชัดนิดนึง เพราะ Content ที่สอดคล้องกับความต้องการของผู้ใช้ จะแตกต่างกับ Content ที่ผู้จัดทำ Web Portal คิดว่า น่าจะสอดคล้องกับความต้องการของผู้ใช้

Personal Web Portal จะหมายถึงตัวแรก มันคือ Personal Web Page ตัวอย่างง่ายๆ คือเป็น Web Page ที่ประกอบขึ้นจาก Website ฉบับย่อ เช่น เมลล์ ราคาหุ้น หรืออื่นๆ ที่เราเข้าไปดูบ่อยๆ ส่วน Content ตัวหลังมักจะหมายถึง Target Advertising ซึ่งเป็นการส่งโฆษณาที่ได้จากการเก็บข้อมูลของลูกค้าคนนั้นๆ

ในความคิดของผมแล้ว ผมจะชอบทั้ง Personal Web Portal และ Target Advertising ตัว Personal Web Portal ช่วยให้ผมสามารถดู Content ที่ผมสนใจจากหลายๆ Website ในหน้าจอเพียงหน้าเดียว โดยที่ไม่ต้องเข้าไปที่ Web Site ทีละ Website เพื่อเรียกดู Content นั้นๆ (สะดวกดีใช่มั้ยล่ะ?)

ผมเคยได้ไปฟัง Presentation จากบริษัท Blyk เขากล่าวว่า “Advertisement isn’t spam, as long as it is relevant. It is information” ในส่วนตัวผมเอง ผมชอบที่จะได้รับคูปองซื้อ 1 แถม 1 จาก Starbuck แต่ในทางปฏิบัติแล้วผมมักจะได้้ อีเมลล์ ที่โฆษณายาแปลกๆ ที่ผมไม่ได้สนใจเสมอๆ (มันน่ารำคาญมั้ยล่ะ?)

ในอดีตการสร้าง Web Page เป็นเรื่องยาก คนที่จะเขียนต้องมีความรู้ความชำนาญค่อนข้างดี คนทั่วไปจึงไม่ได้สนใจที่จะเขียน Personal Web Portal ขึ้นมาเอง

Facebook ได้สร้าง Personal Web Portal สำหรับสมาชิกทุกคน Web Page ดังกล่าวของแต่ละคนจะแตกต่างกันไป และจะสอดคล้องกับความสนใจของแต่ละคน Facebook เรียกหน้า Web Page ดังกล่าวว่า Wall (หรือกระดานข่าว)

แต่ Wall ของ Facebook ก็ยังไม่ได้ เป็น Personal Web Portal อย่างสมบูรณ์ เราไม่สามารถนำ Web Page ต่างๆ มาใส่ไว้ใน Wall ของเราใน Facebook ได้ แต่จะไปโทษ Facebook ก็ไม่ถูก เราต้องเข้าใจก่อนว่า Facebook ไม่ได้ถูกสร้างขึ้นมาเพื่อเป็น Personal Web Portal แต่ Facebook ถูกสร้างขึ้นมาเพื่อเป็นเครื่องมือที่ช่วยให้เราสื่อสารกับเพื่อนๆของเราได้ง่ายขึ้น Personal Web Portal เป็นเพียงผลพลอยได้จาก Facebook เท่านั้น

Source: The Facebook Effect by David Kirkpatrick, Prologue [Read the Book Review].

---------------------------------------------------------------------------------------------------------

Book or Audiobooks?

About the summary: It takes time to finish up a book. And, when you do, sometimes, you want to review what you learn from the book. If you do not make notes as you read, you might have to go through the book once again. This can be time-consuming when you are dealing with a book. But you can still flip through the book and locate what you are looking for

However, when the material is an audiobook, it is extremely hard to locate a specific part of content. Most likely you will have to listen to the entire audiobook once again.

This book summary will help solve the pain of having to go through the book all over again.

I am leaving out the details of the books. Most books have interesting examples and case studies, not included here. Reading the original book would be much more entertaining and enlightening. If you like the summary, you may want to get the original from the source below.

Windows 8!, What a Nice UI!

2011-06-05T04:24:00.000-06:00

I just have a quick view at Windows 8. I really like its user interface! It's like a whole new world. What do you think?

To My FB's Friend, It's time to change password!

2011-05-16T10:55:00.000-06:00

I first heard about this from Security Now shows that Symantec discovered the tokens to access your Facebook account has leaked.

Bad News:

If you use Facebook app and you gave that apps an access to your profile, you might want to read this. Usually, such the apps need to access your profile from times to times (e.g., post on the wall). The apps do not use your password to access your profile. They use Facebook-issued tokens to access your profile. The bad news is these token are leaked. Now, hackers can do whatever your apps can do.

Good News:

The fix is simple just change your Facebook's password. Then, Facebook will reissue the tokens to all your apps. The old tokens that hackers might get a hold of would expire.

Wanna know more?

You can read this link to find out the details.

List of MAC OSX Command Line

2011-04-26T23:07:00.004-06:00

I just find a very useful site which contains a list of MAC OSX command line. Check out [ here ].

Command Line Interface
Terminal is a useful utility, which allows advanced users to work with command line interface (CLI). A lot of programmers prefer this mode due to its flexibility to customize things.

Even for semi-advanced users, Terminal looks scary. One of the problems is that you don't know the command name and their syntax. Documentation is long and some time hard to read. But for sure, it require a lot of effort to comb through the documentation to get what you do using CLI. So a lot of users just give up using CLI.

SS64
Recently, I find a useful site, which lists the most frequently used commands for various platforms, e.g., OSX, Oracle, Windows. The list is not too long and is accompanied with short description. In my opinion, it is a very good reference site. Check out [ here ].

My Personal Use: Copy file content to clipboard.
Let me give you an example use. Do you know that OSX has a command "pbcopy"? To me, I would like to copy the content in a text file to the clipboard. Here is what I do:

Type "less myfile.txt | pbcopy" at the command prompt.
Press Command + V on the application that I would like to paste the content (Note: in Windows, press Ctrl + V).

Pretty cool isnt' it?

List of MAC OSX Command Line

2011-04-26T23:07:00.000-06:00

I just find a very useful site which contains a list of MAC OSX command line. Check out [ here ].

Command Line Interface

Terminal is a useful utility, which allows advanced users to work with command line interface (CLI). A lot of programmers prefer this mode due to its flexibility to customize things.

Even for semi-advanced users, Terminal looks scary. One of the problems is that you don't know the command name and their syntax. Documentation is long and some time hard to read. But for sure, it require a lot of effort to comb through the documentation to get what you do using CLI. So a lot of users just give up using CLI.

SS64

Recently, I find a useful site, which lists the most frequently used commands for various platforms, e.g., OSX, Oracle, Windows. The list is not too long and is accompanied with short description. In my opinion, it is a very good reference site. Check out [ here ].

My Personal Use: Copy file content to clipboard.

Let me give you an example use. Do you know that OSX has a command "pbcopy"? To me, I would like to copy the content in a text file to the clipboard. Here is what I do:

Type "less myfile.txt | pbcopy" at the command prompt.
Press Command + V on the application that I would like to paste the content (Note: in Windows, press Ctrl + V).

Pretty cool isnt' it?

[Book] Why is Facebook successful? What exactly is Facebook?

2011-04-19T06:12:00.001-06:00

Facebook Key Differentiation Factor: Real Identity

What differentiate Facebook from other online social networking website is the true identity. That does not mean you have to use your real name. But you get little benefit from Facebook if you use a fake name.

Facebook mimics this property from the real society. You wouldn't be friends with those you don't know. You tend to make friends through your friends. In Facebook, you would friend people up if you know that person (or you know friends of that person) in the real world.

Personal Web Portal

A portal is a door. So a web portal is a door to the world wide web. A web portal is usually used by Internet Service Provider to display the information relevant to users' interest such as various service plan. Web portals are usually attacked as online marketing tools which present annoying advertisement contents to users.

A personal web portal is just a web portal customized to fit one's interest. When created by marketing agency, personal web portals can mean a target advertising curstomizing to fit users' interest. This is even more scary, because it means one way or another the marketer must be tracking us.

A personal web portal can be very nice if you created it by yourself. Think about it. Think about 100 most recent websites you visited. Are they all distinct? Most likely, the answer is "NO". You tends to visit some website more frequently than the others. For me, there are about 10 websites that I visit frequently. These 10 websites make up about 80% of the 100 websites I recently visited. The other 20% is random websites which I rarely visit.

It would be nice if there is a way to show me the updates on these 10 website I visit most frequently. What I can do is to bookmark these 10 website manually. But then it is quite clumsy. I have to go to each of these website one by one. And, I have to keep updating these websites as my interest changes.

This is where personal web portals come in. A personal web portal is the place which keep track and show you the update on where your most interest lies. When you connect to the internet, it shows you the list of your new mails, news update, stock price, weather forecast, and so on. This would be really nice. This is Facebook.

Social Web Portal

But Facebook takes a personal web portal a step further. Facebook views people as a social animal. Facebook thinks that we are interested in socializing rather than consuming web content. So it gives updates on people you most care about. Facebook is a personal social portal.

Source: The Facebook Effect by David Kirkpatrick, Prologue [Read the Book Review].

---------------------------------------------------------------------------------------------------------

Book or Audiobooks?

About the summary: It takes time to finish up a book. And, when you do, sometimes, you want to review what you learn from the book. If you do not make notes as you read, you might have to go through the book once again. This can be time-consuming when you are dealing with a book. But you can still flip through the book and locate what you are looking for

However, when the material is an audiobook, it is extremely hard to locate a specific part of content. Most likely you will have to listen to the entire audiobook once again.

This book summary will help solve the pain of having to go through the book all over again.

I am leaving out the details of the books. Most books have interesting examples and case studies, not included here. Reading the original book would be much more entertaining and enlightening. If you like the summary, you may want to get the original from the source below.

[Book Review] The Facebook Effect by David Kirkpatrick

2011-04-04T00:26:00.007-06:00

Rating: 4/5

Genre: Non-fiction

Book Review

It is clear from the title that this book is about FACEBOOK. The most widely-used social networking website in the world. Out of curiosity, I read this book after watching the movie “Social Networks”, which is about Facebook. In my opinion, the movie is not based on this book. But based on another book “The Accidental Billionaires: The Founding of Facebook, A Tale of Sex, Money, Genius, and Betrayal” by Ben Mezrich. So this book presents another point of view for Facebook, and unquestionably Mark Zuckerberg.
This book consists of two parts: The history of facebook and the effect of facebook on the world. Personally, I found both part interesting. It lays down the detailed history of Facebook (not in a boring fashion). If you watched “Social Network” or red “The accidental billionaire”, you might think that Mark was a bad guy, who’d care for nothing but himself. He betrayed people over and over to get Facebook to the top of the world. This book presents another perspective. It’s the missing piece of why he did what he did.

The book tells the story of Facebook to the very current time, long after the end of the movie “Social Network”. It also discusses about that happend in the real world before and after Facebook took off. For example, do you know that Facebook exploited attrition of Google and Microsoft to get good deals from them.

Overall, I like this book. The content is good. The writing style is engaging. But it’s a bit long. So I would recommend this book for those who have real interest in Facebook or similar social networking technologies.
In the audiobook version, this book is narrated by David Kirkpatrick himself. Although not my favorite one, he is a very good job. One good thing about self-narrated book is that the author usually know the emotion of the content. He can recall his feeling when he wrote a book. Listing to him is like you are writing the book with him.

Takeaway

There are few things that I learn from this book. They are not general things. They are specific to Facebook:

The innovation of Facebook is the authenticity. Facebook does not force people to use their real name. But you get little benefits if you use fake names.
Google is about information, but Facebook is about communication. It would be interesting to see which one will be the last man standing.
Facebook is not a website. It is a platform. And, platform (e.g., MS-Windows) is a real big thing. Once you have a platform. People can start building things in your way. In short, you do not own a website. You own the world.

Table of Contents

Prologue: The Facebook Effect [Part 1] [ส่วนที่ 1]
Chapter 1: The Beginning
Chapter 2: Palo Alto
Chapter 3: Social Networking and the Internet
Chapter 4: Fall 2004
Chapter 5: Investors
Chapter 6: Becoming a Company
Chapter 7: Fall 2005
Chapter 8: The CEO
Chapter 9: 2006
Chapter 10: Privacy
Chapter 11: The Platform
Chapter 12: $15 Billion
Chapter 13: Making Money
Chapter 14: Facebook and the World
Chapter 15: Changing Our Institutions
Chapter 16: The Evolution of Facebook
Chapter 17: The Future
Postscript

---------------------------------------------------------------------------------------------------------

Book or Audiobooks?

[Book Review] The Drunkard's Walk: How Randomness Rules Our Lives by Leonard Mlodinow

2011-04-01T00:57:00.000-06:00

Rating: 4/5

Genre: Non-fiction

Book Review

If you think that mathematics mainly for academic, this book might change your view. The book talks very little about basic probability principles. Rather, it focuses on how the principles were discovered, what it meant in the old time and the present time, and the fallacy associated to them.

I am quite familiar with probability. So, I find myself reading this book enjoyably. As a student, I was wondering why should study difficult and boring mathematics. If you are like me, you might find this book quite interesting. This book gives the readers the reasons why mathematics matters to, say for example, engineers, statisticians, or even lawyers.

Another interesting part of this book is the history. There are stories of great mathematician and scientists such as Gerolamo Cardano, Galileo Galilei, Blaise Pascal, Jacob Bernoulli, Thomas Bayes, Laplace, Carl Friedrich Gauss. Who would have know that Thomas Bayes was a minister. Pascal suffered from his illness when he did too much thinking.

The book is interesting. It looks at aspects that I usually overlook. It keeps me engaged for most of the content. Overall, I like this book.

Takeaway

Life is full of random events. Good lucks are rare. Bad luck are common. Therefore, bad lucks aren't bad lucks. There are just common things.

Do not be too proud of your talents. Success derives from a combination of talents and good lucks. A lot of talented people fails several times before they succeed.

Despite its important role, chance is not something we can control. The good news is another important factor that we can control is the effort. This means you can increase you chance of success by not giving up. Believe and keep trying.

Do not judge people just from the results. Talent is more important than results, as bad results might just come from bad luck.

Table of Contents

Chapter One: Peering through the Eyepiece of Randomness [Part 1,Part 2]
Chapter Two: The Laws of Truths and Half-Truths [ Click Here ]
Chapter Three: Finding Your Way through a Space of Possibilities [ Part 1, Part 2, Part 3]
Chapter Four: Tracking the Pathways to Success [ Click Here ]
Chapter Five: The Dueling Laws of Large and Small Numbers [ Click Here ]
Chapter Six: False Positives and Positive Fallacies [Click Here ]
Chapter Seven: Measurement and the Law of Errors [ Click Here ]
Chapter Eight: The Order in Chaos [ Click Here ]
Chapter Nine: Illusions of Patterns and Patterns of Illusion [ Part1, Part 2, Part 3, ]
Chapter Ten: The Drunkard’s Walk [ Part 1, Part 2, Final Part ]

---------------------------------------------------------------------------------------------------------

Book or Audiobooks?

[Book] Chances and Successes -- The Drunkard's Walk Wrap-up

2011-02-17T01:41:00.004-07:00

Although regularity can be found in social data, the future of a particular individual is impossible to predict due to

There are infinitely many possibilities,
Minor change can lead to a significant change in outcomes (i.e., the Butterfly Effect), and
People are irrational. They sometimes act against their best interest.

For a particular action, we all owe more to the chance (i.e., luck) than what most people realize.

“Chance is more fundamental than causality.”

Future is unpredictable. Things are uncontrollable. No matter how good you are, your attempts might just turn out in vain consecutively. The good news is one thing that we are in control, our effort, can even out the bad luck. As Bernoulli would say increasing attempts would bring our success rate to our true capability.

“If you want to succeed, double your failure rate.”

It is important to plan, if we do so with our eyes opened. But more importantly, we ought to identify and appreciate the good luck we have, and recognize the random events that contribute to our success. Accept chance events that may cause us grief. Most of all, appreciate the absence of bad luck, the absence of the events that might have brought us down, and the absence of disease, war, famine, and accident that have not or have not yet befallen upon us. THEY ARE JUST CHANCES.

Source: The Drunkard's Walk: How Randomness Rules Our Lives by Leonard Mlodinow, Chapter 10 [Read the Book Review] [Read the Previous Part].

---------------------------------------------------------------------------------------------------------

Book or Audiobooks?

About the summary: It takes time to finish up a book. And, when you do, sometimes, you want to review what you learn from the book. If you do not make notes as you read, you might have to go through the book once again. This can be time-consuming when you are dealing with a book. But you can still flip through the book and locate what you are looking for

However, when the material is an audiobook, it is extremely hard to locate a specific part of content. Most likely you will have to listen to the entire audiobook once again.

This book summary will help solve the pain of having to go through the book all over again.

I am leaving out the details of the books. Most books have interesting examples and case studies, not included here. Reading the original book would be much more entertaining and enlightening. If you like the summary, you may want to get the original from the source below.

[Book] Past-Present Asymmetry

2011-02-10T01:40:00.001-07:00

“If the future is really chaotic and unpredictable, why after the event has occurred does it seem as if we should have been able to foresee them?”

It is easy to reconstruct (or explain) a present from the past. But it s virtually impossible to predict the future from the present. To reconstruct the present, we can look at the past and make up the reason which leads to the present. If we use the same approach to predict (or extrapolate) the future, before long we will end up with infinitely many possibilities. And, even if you can magically pinpoint the future, the Butterfly Effect can mess things up. A minor event from the present to future can change the future entirely. This is to say “the future is unpredictable”.

Source: The Drunkard's Walk: How Randomness Rules Our Lives by Leonard Mlodinow, Chapter 10 [Read the Book Review] [Read the Previous Part] [Read the Next Part].

---------------------------------------------------------------------------------------------------------

Book or Audiobooks?

About the summary: It takes time to finish up a book. And, when you do, sometimes, you want to review what you learn from the book. If you do not make notes as you read, you might have to go through the book once again. This can be time-consuming when you are dealing with a book. But you can still flip through the book and locate what you are looking for

However, when the material is an audiobook, it is extremely hard to locate a specific part of content. Most likely you will have to listen to the entire audiobook once again.

This book summary will help solve the pain of having to go through the book all over again.

I am leaving out the details of the books. Most books have interesting examples and case studies, not included here. Reading the original book would be much more entertaining and enlightening. If you like the summary, you may want to get the original from the source below.

Mac Book Pro Battery

2011-01-14T21:27:00.026-07:00

ผมเพิ่งได้เครื่อง Mac Book Pro มา และพบว่าแบตเตอรี่ของเขามีความจุสูงมากๆ Apple อ้างว่าใช้ได้นานถึง 9 ชั่วโมง แต่ในเครื่องที่ผมใช้ก็คำนวณได้ 9 ชั่วโมงกว่าๆ ซึ่งก็นานมากอยู่ดี ถ้าต้องขึ้นเครื่องบินไปต่างประเทศ คงไม่ต้องกังวลเรื่องแบตเตอรี่หมดบนเครื่องอีกแล้ว

อายุการใช้งาน

ก่อนจะคุยกันเรื่องอายุการใช้งานเรามาทำความรู้จักกับศัพท์ใหม่กันก่อน ศัพทที่ว่าคือ Charge Cycle

Charge cycle 1 รอบหมายถึงการใช้แบตเตอรี่จนหมดเกลี้ยง 1 ครั้ง ถ้าเราใช้แบตเตอรี่ไป 30% หนึ่ง แล้ว recharge นั่นหมายถึงเราใช้งานไป 30% ของ 1 Charge Cycle เราจะต้องใช้แบตเตอรี่อีก 70% ของความจุทั้งหมดจึงจะครบ 1 Charge Cycle

Apple อ้างว่าแบตเตอรี่ของเขามีการใช้อายุการใช้งานดังนี้

หลังจาก 1000 Charge Cycles ความจุของแบตเตอรี่จะอยู่ที่ 80% ของความจุแรกเริ่ม
การใช้งานปกติจะทำให้แบตเตอรี่ใช้ได้ถึง 5 ปี

ความจุของแบตเตอรี่

ทางมุมขวาบนของ Desktop เราจะเห็น Mini Toolbar อยู่ ลองสังเกตุ icon รูปแบตเตอรี่ดู ด้านข้างจะมีสถานะอยู่

Charged: ระหว่างใช้งานเครื่องด้วยไฟตรงและแบตเตอรี่เต็มอยู่
Percentage: เปอร์เซ็นต์ของแบตเตอรี่
เวลา:

ระหว่างชาร์จ: เวลาที่ต้องใช้ในการชาร์จแบตเตอรี่ให้เต็ม
ระหว่างที่ไม่ได้ชาร์จ: เวลาที่ยังใช้งานได้จนกว่าแบตเตอรี่จะหมด (ดูรูปประกอบ)

ชาร์จได้ตลอดเวลา

Apple ใช้เทคโนโลยี Lithium-Ion Battery ซึ่งทำให้เราสามารถชาร์จแบตเตอรี่ได้ตลอดโดยไม่ต้องรอให้แบตเตอรี่หมดเสียก่อน ถ้าเราจำกันได้จะมีคนเคยบอกว่าแบตเตอรี่รุ่นเก่าๆ ที่เป็น Nickel-based Battery จะต้องใช้ให้หมดก่อนค่อยชาร์จไม่งั้นแบตเตอรี่จะเสื่อมเร็ว นั้นเป็นเพราะถ้าชาร์จระหว่างที่แบตเตอรี่ไ่ม่หมดจะมีละอองคริสตัลไปเกาะที่สาร Nickel ทำให้กระแสไฟไม่สามารถไหลเข้าไปที่ Nickel ได้ แต่ Lithium-Ion ไม่มีปัญหานี้ เราจึงสามารถชาร์จได้ตลอดเวลา

นอกจากนี้หลักจากที่แบตเตอรี่เต็มแล้ว Mac Book จะตัดกระแสไฟจาก Adapter ไม่ให้เข้าไปที่แบตเตอรี่อีกด้วย ลองเข้าไปดูที่ System Preference ขณะที่ไม่ได้ชาร์จแบตเตอรี่อยู่ กล่อง 'Power Adapter' จะถูกไฮไลท์ด้วยพื้นหลังสีฟ้า

วิธีการชาร์จของ Apple

Apple จะชาร์จแบตเตอรี่ด้วยวิธี 2 วิธีด้วยกัน

Fast Charge: ชาร์จต่อเนื่องจนกระทั่ง Capacity ของแบตเตอรี่อยู่ที่ 80%
Trickle Charge: ชาร์จและหยุดสลับกันไป จนกระทั่ง แบตเตอรี่เต็ม (Trickle Charge จะช่วยถนอมแบตเตอรี่ไม่ให้เสื่อมเร็ว)

แล้วควรจะชาร์จตลอดเวลาหรือไม่?

ตอบสั้นๆว่าไม่ควร Apple บอกว่าเราควรจะให้ electron ไหลผ่านแบตเตอรี่เป็นคร้ั้งคราว Apple แนะนำให้เราใช้งานดังนี้

ดีที่สุด: สำหรับผู้ที่ต้องเดินทาง ให้เสียบไปใช้งานที่ office หรือที่บ้าน แล้วใช้งานระหว่างอยู่บนรถ เช่น บน BTS (แต่อย่าลืมว่าคนอเมริกันเดินทางมากกว่าคนไทยมากนะ)
สำหรับผู้ที่ใช้ Macbook Pro แทน Desktop: ให้ใช้แบตเตอรี่ให้หมดแล้ว recharge (1 full charge cycle) เดือนละหนึ่งครั้ง (อันนี้เป็นข้อแนะนำสำหรับคนที่ตั้งเครื่องไว้ที่โต๊ะแล้วเสียบไฟไว้ตลอด)

ฟังดูแล้วยุ่งใช่มั้ยครับ ส่วนตัวผมคิดว่าผมจะใช้แบบสบายๆ มีที่ชาร์จไฟก็ชาร์จ ไม่มีก็ไม่ต้องชาร์จ ไม่ต้องไปดิ้นรนหาที่ชาร์จเหมือนเวลาใช้ Notebook ที่มีความจุแค่ชั่วโมงเศษ

อะไรทำให้ผมชอบ Macbook pro

แบตเตอรี่เป็นอีกสิ่งนึงที่ทำให้ผมชอบ Macbook Pro เมื่อก่อนเคยใช้ Notebook ยี่ห้ออื่น ต้องคอยกังวลว่าแบตจะหมด และต้องคอยถอดแบตเตอรี่ออกเพราะกลัวแบตเตอรี่จะเสื่อม Apple ออกแบบสินค้าให้เหมาะกับ Lifestyle ของผู้ใช้จริงๆ ตอนนี้ผมไม่ต้องกังวลว่าแบตเตอรี่จะหมดแล้ว (7 ชั่วโมงกว่า จะหมดก็ให้มันรู้ไป) แล้วก็ไม่ต้องคิดมากเรื่องต้องถอดแบตเตอรี่ออกเพราะกลัวมันจะเสื่อม (ยิ่งถ้าเสียบไปตลอดจะทำให้แบตเตอรี่เสื่อมด้วยซ้ำไป)

ที่มา: Apple's Website เรื่อง [แบตเตอรี่] และ [แบตเตอรี่ของ Notebook]

[Book] Butterfly Effect

2010-12-30T05:48:00.006-07:00

No, we are not talking about the movie by Ashton Kutcher. We are going to talk about the Butterfly Effect which is a concept in chaos theory, which says

A flap of butterfly's wings in Brazil can set out a tornado in Texas.

More generally, few insignificant random events can cause a big impact. This phenomena occur a lot in our daily life. But perhaps, it is referred to as fate, rather than the Butterfly Effect. For example, had Bruce Willis not gone to at attend an Olympic event in 1984, he might have not been a star today, or had you not gone to study abroad, you might have not found the love of your life.

Source: The Drunkard's Walk: How Randomness Rules Our Lives by Leonard Mlodinow, Chapter 10 [Read the Book Review] [Read the Previous Part] [Read the Next Part].

---------------------------------------------------------------------------------------------------------

Book or Audiobooks?

About the summary: It takes time to finish up a book. And, when you do, sometimes, you want to review what you learn from the book. If you do not make notes as you read, you might have to go through the book once again. This can be time-consuming when you are dealing with a book. But you can still flip through the book and locate what you are looking for

However, when the material is an audiobook, it is extremely hard to locate a specific part of content. Most likely you will have to listen to the entire audiobook once again.

This book summary will help solve the pain of having to go through the book all over again.

I am leaving out the details of the books. Most books have interesting examples and case studies, not included here. Reading the original book would be much more entertaining and enlightening. If you like the summary, you may want to get the original from the source below.

[Book] Confirmation Bias and Sharp Shotter Effect

2010-12-20T20:16:00.002-07:00

Confirmation bias
People are really good at recognizing patterns, even though a pattern isn’t a pattern. Once they find a pattern, it’s hard for them to let go. People tend to prove themselves correct, rather than find out the truth. This is called confirmation bias.

Sharpshooter effect
It’s just like having a mediocre sharpshooter shoots a blank paper, and draws a picture afterwards. Consider following random results. Do you see any pattern?

I don’t. But if you do, you may consider to work in forensics science or as a government agency.
Now let’s try again. I will just rearrange the above random string in a rectangle format. Here is the result:

Suppose the rectangle is a geographical area. If ‘1’ represents places where terrorism breaks out during the last few years. Then we might draw a conclusion that the left of the rectangle is a highly sensitive area. This experiment tells us that the pattern can be misleading. The location of sensitive areas may be just a random string crafted up to deceive authorities.

Source: The Drunkard's Walk: How Randomness Rules Our Lives by Leonard Mlodinow, Chapter 9 [Read the Book Review] [Read the Previous Part] [Read the Next Part].

---------------------------------------------------------------------------------------------------------
Book or Audiobooks?

There is one more reason that may encourage you to go for the audiobook version. You can get it now for FREE. Audible offers you a free trial for 14 days. Even if you get the book and cancel the subscription right away (so that you don't have to pay), you can keep the book. And, don't worry if you lost the audiobook file. Just log into audible.com. You can keep downloading the over and over again.

About the summary: It takes time to finish up a book. And, when you do, sometimes, you want to review what you learn from the book. If you do not make notes as you read, you might have to go through the book once again. This can be time-consuming when you are dealing with a book. But you can still flip through the book and locate what you are looking for

However, when the material is an audiobook, it is extremely hard to locate a specific part of content. Most likely you will have to listen to the entire audiobook once again.

This book summary will help solve the pain of having to go through the book all over again.

I am leaving out the details of the books. Most books have interesting examples and case studies, not included here. Reading the original book would be much more entertaining and enlightening. If you like the summary, you may want to get the original from the source below.

[Book] Hot hand fallacy

2010-11-21T20:46:00.001-07:00

Hot hand fallacy states that if performing well in last consecutive trials, a person might perform well in the next trials. In fact, the streak (of well-performance) may just be because of pure chance. If this is the case, the results in the few consecutive trials infer nothing about the next trials.

Hot hand fallacy is perceived in various fields such as sport or business. We usually judge people (e.g., basketball players or companies) by statistics. But we usually misled by a hot hand fallacy. When a good player makes several baskets consecutively, we tend to think that his hand is “hot”, and that his teammates should give him the ball. So if an average player makes several baskets consecutively, does is mean that his is better than a good player? No, because if he is better, his statistics would have been better. The fact that he makes a lot of baskets consecutively implies that he might miss a lot of baskets too. We just don’t know when it will happen.

What about when you see a company performs above average for 12 consecutive year? Would you think that the managements working for that company were great? Alternatively, would you think that the streak is just a chance? Let's analyze the chance, shall we?

Let’s flip a coin. What are the chance that you will toss a head? One in two, right? What about 2 heads in rows? One in four right? Now think of head as when a company performs above average and a tail as when a company performs below the average. The chance of one company will perform above average for 12 consecutive months is just the chance of tossing heads for 12 consecutive time, which is 1 in 4096, pretty unlikely, isn’t it? So we might think that the management must be really good to beat the odds of 1 in 4096. Not quite!

Why not? Don't forget that we have more than one company in the market. Let’s say we have 1000 companies in the market. What are the chance that one of those companies will perform above average for 12 consecutive years? That would be 1 in about 4.62. So it's not very low, right?

So what exactly does it mean? For a company, it's still hard to perform above the average for 12 consecutive months. But it's not hard to find one of them which performs above the average for 12 consecutive months.

Source: The Drunkard's Walk: How Randomness Rules Our Lives by Leonard Mlodinow, Chapter 9 [Read the Book Review] [Read the Previous Part] [Read the Next Part].

---------------------------------------------------------------------------------------------------------
Book or Audiobooks?

[Book] People, Perception, Perfection, and Randomness

2010-11-13T11:01:00.005-07:00

Perfection requires perfect perception. It is hard to achieve perfection, since the data we perceives is rarely perfect. So how do we determine whether what we perceive is true. In a more technical term, how do we accept or reject the hypothesis based on what we perceived? In this respect, statisticians resort to "Significant Testing" in order to make decision based on observations.

"Human perception is very narrow. There is only about 1 degree of visual angle around the retina center which has high resolution. Outside this region, the resolution drops off sharply. Therefore, we tend to move our eyes a lot to compensate for the narrow visual area."

People cannot perceive randomness when they see it, and they cannot produce it when they try. For example, if a random number generator generates several consecutive ‘0’, how much would you trust that generator? When Apple first introduced a shuffle function with true random in their iPod, some songs came up few times in a short playlist. People complained that the shuffle function isn't truly random. Apple ended up using less random function to make people feel that the shuffle function was more random. People cannot differentiate between a process being random, and the random outcomes of the process.

Source: The Drunkard's Walk: How Randomness Rules Our Lives by Leonard Mlodinow, Chapter 9 [Read the Book Review] [Read the Previous Part] [Read the Next Part].

---------------------------------------------------------------------------------------------------------
Book or Audiobooks?

[Book] The Dawn of Statistics

2010-10-21T04:10:00.005-06:00

Statistics began as early as 1066, when William the conqueror, the Duke of Normandy, conquered and became the King of England. He would like to find out what exactly he did conquer and how much tax he can collect. So he sent out two groups of inspectors to men to do some survey on land and livestock. At that time, people believed that it is the God’s will to let people live or die. So, a survey of people as well as how they born and die were forbidden. As time changes, people changes. In later time, people began to believe that study of population is not against the God’s will, but is the way to understand him better. In the 16th century, the London Bill of Mortality was drafted. It was the first attempts to record people’s birth and death.

"Statistics can provide insights into the system from which the statistics are derived."

Source: The Drunkard's Walk: How Randomness Rules Our Lives by Leonard Mlodinow, Chapter 8 [Read the Book Review] [Read the Previous Part] [Read the Next Part].

---------------------------------------------------------------------------------------------------------
Book or Audiobooks?

[Book] Measurement and the Law of Errors

2010-10-02T00:50:00.002-06:00

Ancient Experiment: Science or Art
In the old time, scientists perform experiment, and make the best intuitive guess of what the result should be. And, if they were to repeat the experiment, they could get totally different results. They just lacked a standard for measurement.
In other words, they use feeling rather than scientific method. Is this science? Or, is it art? “Any variation within a margin of error should be ignored.”

The Law of Errors: The Bell Curve
Given a set of observations, Pascal tells us how expected value of the observations can be computed. But the expectation is just what you expect, not the real observations. The real one could deviate from the expectation. Now, the question is “by how much the observations deviate from the expectation?”

Decades of study have shown that the deviation pattern follows what mathematicians call the normal distribution, often referred to as the Bell Curve due to its shape. The Bell Curve is characterized by two parameters: Expectation (what to expect of the observation) and Standard deviation (How much the observations deviate from the expectation, i.e., how reliable the expectation is).

So What?
Modern scienticfic measurement is not based on feeling. It iterates the same experiment for several times, and finds a valid representation. In most cases, expectation is a valid representation. And, we can tell how reliable the expectation is by looking at the standard deviation.

Source: The Drunkard's Walk: How Randomness Rules Our Lives by Leonard Mlodinow, Chapter 7 [Read the Book Review] [Read the Previous Part] [Read the Next Part].
---------------------------------------------------------------------------------------------------------
Book or Audiobooks?

[Book] False Positives and Positive Fallacies

2010-09-28T05:14:00.002-06:00

Conditional Probability

We learned earlier that more details can lead to more restriction and reduce the corresponding probability. More specifically, the probability of event A is always greater than the probability of events A and B.

But details do not always reduce the probability. It can increase the probability by shrinking the sample space. We can be more sure that a specific outcome will occur if we can cross off some of the sample space. This is known as “Bayes’ Theorem”.

Bayes’ Theorem

If you recall, Bernoulli considered the question

“Given a specified number of white and black balls in an urn, what is the probability of drawing a black ball?”

There is a minister and mathematician, who was interested in the following problem

“Given that one or more balls has been drawn, what can be said about the number of white and black balls in the urn?”

His name is Thomas Bay. He coined two terms.

Prior probability: The basic probability or initial estimation of an event
Posterior probability: The probability of the same event, when given more information (e.g., some of the balls are removed).

False Positive

Consider an HIV testing scenario. With 10,000 test subjects, suppose the result is shown below:

Suppose your blood test is HIV positive. What is the chance that you are not infected? It’s not uncommon to think that the chance is pretty slim (i.e., 10 in 10,000 or 1%). And, you might think that you will not live long enough to see your grandchild.

This is another fallacy. Look at what you are considering. You are comparing false positive test to all test subjects regardless of their test results. What you should really looking for is as follows

“Among those whose blood test is positive, how many people are not infected?”

Then, you will see that the error is 10 (false positive) in 10+1 (blood test is positive). The error is around 91%! On the other hand, there is no chance (0), that you will be infected if you blood test is negative. So you might consider taking the test again, if you blood test might turn out positive. But you do not need to take another test if your blood test is negative. The test result per se is necessary but not sufficient. We need to factor in the relevant sample space.

Fallacy: Prosecutor’s Fallacy

Prosecutor’s fallacy is statistical misconceptions when making legal arguments. Common prosecutor’s fallacy includes, for example, drug test, and DNA test.

Source: The Drunkard's Walk: How Randomness Rules Our Lives by Leonard Mlodinow, Chapter 6 [Read the Book Review] [Read the Previous Part] [Read the Next Part].

---------------------------------------------------------------------------------------------------------
Book or Audiobooks?

Probability, Ratio, and the Law of Large Numbers

2010-09-19T09:23:00.002-06:00

Probability and Ratio

You probably know about probability and ratio. Suppose I put 70 of black balls and 30 of white balls in an urn. General statements would be

The Ratio of black balls (when comparing to all the balls in the urn) is 7:10
If I draw a ball from the urn, the Probability that I would draw a black ball would be 7 in 10

Are They Different?

Ratio and Probability look very similar. For the above example, both the ratio and the probability is 7 in 10. But, in fact, they differs:

Ratio is an act in the past. It is deterministic and measurable. You put 70 black balls in an urn. That's make the ratio 7 in 10.
Probability is an act in the future. It is probabilistic and uncertain. The chance to draw a black ball is 7 in 10. But it doesn't mean that, if you draw 10 balls, 7 of them would be black.

This definition discrepancy is filled up by what mathematicians known as the Law of Large Number.

The Law of Large Number

"It is always possible to have a finite number of observations such that the observed probability matches closely with the underlying ratio."

The Law of Large Number was stated without proof by Gerolamo Cardano in the 15th century, and was formally proved by Jacob Bernoulli in the 17th century. It is therefore also known as the "Bernoulli's Theorem" or a "Golden Theorem".

Loosely speaking, the law of large number say that the probability and the ratio would be the same if you carry out a sufficient large number of experiments.

Does It Have Implication in Real Life?

Yes. Here is one of them.

Suppose you are good at something. But you keep failing due to the randomness (i.e., bad luck). Then you should double (or triple) your effort (number of trials). Your effort (i.e., trial) will wipe out the bad luck (i.e., randomness), and people will see your true performance (i.e., ratio).

Source: The Drunkard's Walk: How Randomness Rules Our Lives by Leonard Mlodinow, Chapter 5 [Read the Book Review] [Read the Previous Part] [Read the Next Part].

---------------------------------------------------------------------------------------------------------
Book or Audiobooks?

A new blogspot test message no. 5 on Sept. 18

2010-09-17T23:50:00.001-06:00

Gods and Expectation

2010-09-16T01:22:00.002-06:00

Blaise Pascal

Blaise Pascal is known as the person who invented the Pascal's Triangle, whose elements are the number of ways to arrange N objects in M places.

But, the story that drew my interest is that he is also the inventor of expectation. And, even more interesting is how he came up with the concept of expectation. Here we go....

Gods, Pious, and Expectation

Pascal conceived the expectation concept when he pondered whether he should believe in Gods. This is what he thought. If God exists the payoff for being pious is infinity. However, if God does not exist, the payoff will be insignificant. To account for the uncertainty of Gods' existance, he multiplied the probability that God exists and does not exist with correspondent payoffs, and added both the products together. That is what he called "expectation". Since the result was infinity, he concluded that regardless of whether God exists everybody should be pious.

Source: The Drunkard's Walk: How Randomness Rules Our Lives by Leonard Mlodinow, Chapter 4 [Read the Book Review] [Read the Previous Part] [Read the Next Part].

---------------------------------------------------------------------------------------------------------
Book or Audiobooks?

Update on NS 2.35 Installation: Command not Found

2010-09-15T03:44:00.000-06:00

During the last week, I have got few email about my previous NS2 installation.

The Error Message

After the installation some one type "ns" and get the following error
>>nsbash: ns: command not found
This could be because you have not set the $PATH variable. Therefore, the OS does not know where to look for the command "ns".

Has NS2 Been Installed Correctly?
Here is what you have to do

Go to your directory ns2
If you type "ls", you should see the file "ns.exe"
Type "./ns".
NS2 should run correctly.

What If I Want to Run NS2 in Different Directory

Well, you will have to make the command "ns" globally available. There are two way to achieve this

Set the $PATH variable in the file .bashrc located in your home directory (See the slide and the previous post)
Create a symbolic link to the OS search path such as "/usr/local/bin". To do this, type the followings:

>>cd /usr/local/bin
>>ln –s /home/T_Bear/ns-allinone-2.35-RC3/ns-2.35/ns.exe

This statement works for my system. You might have to adjust the directory accordingly.
Note: "ln -s" is a command which creates a symbolic link to the following input argument to the current directory [see here for more detail]
NS2 should run now correctly.
NS 2.35 Installation Slides
I updated the slide accordingly. Please have a look below:

Ns-2.35 Installation

View more presentations from Teerawat Issariyakul.

The Birthday Problem

2010-09-10T06:08:00.003-06:00

Given that everyone’s birthday is absolutely random, how many people
must be in the room such that there is more than even chance (at least
50%) that

Another person would have the same birthday as you (ANS: 365/2 =
183 persons)
Two persons would have the same birthday (ANS: 23 persons)

The difference is that you fix the date in the former. But you let the date vary in the latter. It is obvious that you would need less people in the latter than in the former. But the surprising result is that it is a lot less.

This result can explain few strange and embarrassing incidents. Canadian lottery officials planned to awards cars to five people who own winning lottery tickets. The system ended up generating the same number twice. The person who has that number won two cars.

Given the number of the first winning lottery, the chance that the second lottery will repeat the first one can be made very slim. However, the chance that two winning tickets are the same is not.

Source: The Drunkard's Walk: How Randomness Rules Our Lives by Leonard Mlodinow, Chapter 3 [Read the Book Review] [Read the Previous Part] [Read the Next Part].

---------------------------------------------------------------------------------------------------------
Book or Audiobooks?

C++ and OTcl Linkage: Result — Passing Values between C++ and OTcl domains

2010-09-06T20:57:00.000-06:00

ote: The content in this series is extracted from the book, Introduction to Network Simulator NS2. You may have to read chapter 3 of the book for better understanding.

Introduction
This post is the second post in the series on C++ and OTcl Linkage:

   1. Why Two Languages?
   2. Binding C++ and OTcl classes [Main steps, The mechanism].
   3. Variable binding
   4. OTcl command: Invoking C++ statements from the OTcl domain [ Getting Started, Invocation process, Binding OTcl and C++ ]
   5. Eval: Invoking OTcl statements from the C++ domain
   6. Result: Passing Values between C++ and OTcl domains
   7. Object binding and object construction process.
In the previous post, I blogged about an approach to invoke OTcl statements from the C++ domain using function evalc(...) and evalf(...). This post discusses the way to pass results between C++ and OTcl domains using function result(...).

Passing Values Between C++ and OTcl

View more presentations from Teerawat Issariyakul.
======================================================
T. Issaraiyakul and E. Hossain, “Introduction to Network Simulator NS2”, Springer 2009.

You may also find lecture notes and other resource at the following website: http://www.ece.ubc.ca/~teerawat/NS2.htm

Sample Space and Gambling

2010-09-01T03:01:00.004-06:00

The Dawn of Sample Sapce

Gerolamo Cardano was an physician, a gambler, and a mathematician. Early in his career, he discovered the concept of sample space, and tried to publish the concept in a book named “The book on Games of Chance”. The manuscript was rejected.

He did not try to published it again. Instead, he used the concept to make a fortune out of gambling. The book was published after his death in 1663. Here is the quote from the book.

“The possible outcomes of a random process can be thought of as a point in the space.”

This space of all possible outcomes is later known to as “sample space”.

Combination, Permutation, and Gambling

To see how sample space helps in gambling, let’s look at following examples:

A Game of Flipping Two Coins

Let flips two coin and bet on the number of heads. There can be no head, one head, and two head. Before the time of sample space, it was believed that each of these 3 outcomes are equally probable.

If you look closely, there is one way to get no head (tail-tail) and one way to get two heads (head-head). But there are two ways to get one head (head-tail and tail-head). If you are a time traveller, you should try to return to 15th century and bet more on one head. It is more likely to win when you bet on the one-head outcome.

A Game of Throwing Three Dice

Let throw three dices. There are 6 ways to get a total of 9, and 6 ways to get a total of 10. One might think that getting 9 and getting 10 are equally probable. But in fact, the total of 10 occurs more frequent. The reason is that the combination of 6+3+1 = 6+1+3 = ... = 10 occurs more frequent that of 3+3+3 = 9. This is what mathematician call "permutation''.

"The chance of an event depends on the number of ways in which it can occurs.''

Source: The Drunkard's Walk: How Randomness Rules Our Lives by Leonard Mlodinow, Chapter 3 [Read the Book Review] [Read the Previous Part] [Read the Next Part].

---------------------------------------------------------------------------------------------------------
Book or Audiobooks?

C++ and OTcl Linkage: Eval — Invoking OTcl statements from the C++ domain

2010-08-30T00:42:00.001-06:00

The Interpretation of Randomness

2010-08-27T05:55:00.002-06:00

How much do you know about randomness? What does it mean by a random process? Well, a lot of people would say that a random process is a process whose outcomes cannot be predicted. Clean and simple, and nice for a lot of people.

But this definition is quite vague to mathematician. Mathematicians have something for preciseness. When you say a circle is round, they would ask how round, and you would not know how to reply to them. But if you ask a mathematician how round is a circle, the answer would be 3.14 x R x R where R is the radius.

Likewise, the above definition for a random process is not precise enough. For mathematician, there are at least two interpretation for a random process:

(i) Frequency interpretation: A process is said to be able to generate random numbers when the observed outcome conform to the underlying probability.

(ii) Subjective interpretation: Observed outcomes are said to be random if they cannot be predicted.

A perfect dice creates random numbers from 1 to 6 according to the former interpretation since, in a long run, the outcomes would be each of the numbers (i.e., 1 to 6) with probability 1/6. However, since the outcomes are predictable, they are not random by the latter definition.

On the other hand, a real dice is not perfect. The probability at which a dice would land on each side is not 1 in 6. It may take millions or billions of observation. But finally, you will observe that one side would be more favorable than the others. As a result, throwing a real dice is not random by the former definition. But it is by the latter, since the outcomes are not predictable.

Source: The Drunkard's Walk: How Randomness Rules Our Lives by Leonard Mlodinow, Chapter 3 [Read the Book Review] [Read the Previous Part] [Read the Next Part].

---------------------------------------------------------------------------------------------------------
Book or Audiobooks?

[NS2] Error message: Invalid command

2010-08-22T19:39:00.000-06:00

Last week, I've got few messages asking me similar questions. The question was why do I see the following error message when running NS2 and how do I fix it?

invalid command name

The Cause of the Error Message

This message is an OTcl error message, saying that the NS2 (or more precisely the OTcl interpreter) does not understand the current statement.
For example, by default, the following OTcl statement will cause an error:
Agent/GPSR set sport_ 255

since NS2 does not understand "Agent/GPSR"

The Syntax of OTcl

OTcl is an interpreter which interprets OTcl command line by line. Each line begins with a keyword such as "set", "new", etc.

The above example statement begins with "Agent/GPSR" which is known to OTcl as a string, not a command. Therefore, OTcl creates an error message when encountering this message.

How Do We Fix It?

To fix this problem, you first need to understand you own need. The above statement has two problem

1. Agent/GPSR is unknown to NS2. You need to declare this class before you can use it. To do so, please read the following post.
2. In most cases, you would not set the value of a variable belonging to a class. But you will do so with a variable belonging to an object. So, after fixing the former problem, you will have to do the following:

set agent [new Agent/GPSR]
$agent set sport_ 255

where first you create an object $agent of class Agent/GPSR. Then you set the instvar sport_ of $agent to be 255
======================================================
T. Issaraiyakul and E. Hossain, “Introduction to Network Simulator NS2”, Springer 2009. Buy it now from

You may also find lecture notes and other resource at the following website: http://www.ece.ubc.ca/~teerawat/NS2.htm

The Greek, the Roman, and the Mathematics

2010-08-18T02:27:00.003-06:00

The Greek and Their Mathematics

Most greek Mathematics are mainly about geometry. They do not believe in probability since

They believe that chance is governed purely by Gods.
Their number system is very difficult to work with. Algebra and arithematics had not existed in their time. They don’t even have the number zero nor fraction.

The Roman and the Half-Proofs

It is hard to prove a certain fact. It could be easier to break the fact into two independent parts, and proves each part independently. Clean and simple, isn't it? Well, this is probably why the Romans used it to prove innocence.

In the Roman time, a person can be condemned if witnesses testified against that person. The number of witnesses required to condemn a person varies according to the defendant's social status.

The idea behind this strategy is that two half-proofs make up a full proof. So, let's find 2 of half-proves, add them up, and get the full-proves. Suppose that each of half-proves can be in correct with probability of 0.5. When we add them up, the probability for the fact being correct is 1, right? Wrong!!

Well, to prove the fact, we need BOTH the halves to be correct. So the probability of the entire fact being correct is 0.5 x 0.5 = 0.25, not 0.5 + 0.5 = 1.

Source: The Drunkard's Walk: How Randomness Rules Our Lives by Leonard Mlodinow, Chapter 2 [Read the Book Review] [Read the Previous Part] [Read the Next Part].

---------------------------------------------------------------------------------------------------------
Book or Audiobooks?

C++ and OTcl Linkage: OTcl Commands — Binding OTcl and C++

2010-08-16T00:50:00.001-06:00

argc is the number of input arguments
argv is an array of input arguments. It stores all the input parameters of the OTcl command, where argv[0] stores a string "cmd", argv[1] stores a string of the first input argument, and so on.

Example

The OTcl command invocation was

$obj show-delay

This statement is passed down to instproc unknown of class SplitObject, which in turn executes

$self cmd $args

where $self is $obj and $args is "show-delay". This statement is passed on to the C++ function command(argc,argv), where argc = 2, argv[0] = "cmd", and argv[1] = "show-delay". Since argc and argv match both the "if" conditions (Lines 3 and 4), Line 5 is executed. And, a string "show-delay" is shown on the screen.

Return Value

As a final note, Line 9 is the default statement, which is executed if none of the above "if" conditions matches. Here it invokes the (same) function command of its base class (here class TclObject is the base class of class MyObject), and passes (argc,argv) as input arguments. The value returned from function command(...) of class TclObject will be returned to Line 9, and will be returned to the caller.
======================================================

T. Issaraiyakul and E. Hossain, “Introduction to Network Simulator NS2”, Springer 2009.
You may also find lecture notes and other resource at the following website: http://www.ece.ubc.ca/~teerawat/NS2.htm

Availability Bias

2010-08-14T00:36:00.002-06:00

A Trick Question You Might Want To Try With Your Friends

Let me ask you a question. Among English 6-letter words, which of the following is more probable?

Find a word whose fifth letter is ‘n’.
Find a word ending with ‘ing’.

The correct one is the former. But if your answer is the latter, don't worry about it. It is normal. To see why, let me ask you another question.

What is the 5th letter in a 6-letter word with suffix `ing'? It's `n', isn't it?. The latter case is just a special case (i.e., subset) of the former, and is therefore less probable.

Mathematics and Implication

In Mathematics, suppose we have events A and B. Then,

P(A and B) <= P(A)
P(A and B) <= P(B)

However, most people are highly influenced by relevant information. They tend to think that statements with greater relevant details are more probably. This is a common fallacy which happens extensively in our daily life.

More Examples

Let me ask you again. Which of the following is more porbably?

(i) "A suspect hates the victim and he kills the victim.'' OR ``A suspect kills the victim.''
(ii) It will be cloudy and rain tomorrow.'' OR ``It will rain today.''

A lot of people tends to choose the former, since it provides supporting reasons. But think about it. More details impose more restriction on the statement. And, more restriction means less probable. This is a common fallacy in our daily life. Remember, more details leads to less probability, not more probability.

Source: The Drunkard's Walk: How Randomness Rules Our Lives by Leonard Mlodinow, Chapter 1 [Read the Book Review] [ Read the Previous Part ] [Read the Next Part].

---------------------------------------------------------------------------------------------------------
Book or Audiobooks?

Regression towards the Mean

2010-08-10T02:58:00.002-06:00

A result which falls far from the mean tends to be closer to the mean during the next attempt. Failing something consecutively does not mean that the next attempt will not succeed. Attempts and successes are not linearly related.

Future is unpredictable, but there is one good news. If you are good (i.e., the mean is good enough), you will finally succeed (i.e., reach the mean). Do not give in, even if you have failed (i.e., fall off the mean) consecutively.

“Genius does not guarantee success, but it is seductive to assume that success must come from genius.”

The logic behind the “regression towards the mean” theorem is as follows. Suppose your average test score is 50. Now, let’s take a test. Suppose that you’ve got 40. If your next test scores less than 40, which is further away from the mean, your average won’t be 50. It has to be lower than 50 which contradicts to what we assume at the beginning.

Source: The Drunkard's Walk: How Randomness Rules Our Lives by Leonard Mlodinow, Chapter 1 [Read the Book Review] [Read the Previous Part] [Read the Next Part].

Source: The Drunkard's Walk: How Randomness Rules Our Lives by Leonard Mlodinow, Chapter 1 [Read the Book Review] [Read the Next Part].

--------------------------------------------------------------------------------------------------------- Book or Audiobooks?

C++ and OTcl Linkage: OTcl Commands -- Invocation process

2010-08-08T23:39:00.000-06:00

Note: The content in this series is extracted from the book, Introduction to Network Simulator NS2. You may have to read chapter 3 of the book for better understanding.

Introduction
This post is the second post in the series on C++ and OTcl Linkage:

   1. Why Two Languages?
   2. Binding C++ and OTcl classes [Main steps, The mechanism].
   3. Variable binding
   4. OTcl command: Invoking C++ statements from the OTcl domain [ Getting Started, Invocation process ]
   5. Eval and result: Invoking OTcl statements from the C++ domain
   6. Object binding and object construction process.

In the previous post, I blogged about OTcl command. I took you to see how to create a OTcl command in C++ and invoke the command from the OTcl domain. how C++ and OTcl classes are bound together. In this post, I will explain the key steps for OTcl command invocation.

Objective of this post
From the previous post, our OTcl file looks like this:

1 set obj [new MyOTclObject]
2 $obj show-delay

In this post, we are going to look at the main step OTcl does when seeing

$obj show-delay

Key Steps:

Step 1: Look for the instproc

This is a simple structure of OTcl: Object name followed by the name of instproc. So, in the first step, OTcl see if the instproc "show-delay" is defined in the class of $obj. If so, it will execute the instproc. Otherwise, it will go to Step 2.

Step 2: Look for the default instproc "unknown"

OTcl has a special instproc called "unknown" which will be invoked if the invoked instproc is not defined in the current class.

To see this, recall from the previous post that when executing "otcl.tcl" you will see

Now let's add the followings to the beginning of the file "otcl.tcl".

3 MyOTclObject instproc unknown args {
4     puts "Invoking unknown"
5 }

Now if you try to run "otcl.tcl", you will see

Since the instproc unknown is defined in the class of $obj, OTcl invokes what defined in the instproc unknown, and moves to the next statement.

Step 3: Move to the base class
OTcl is an object oriented program. According to the inheritance principle, if OTcl cannot find the method in the current class, it will moves to the base class and look for the method again. So, in this step, OTcl moves to the base class and repeat Step 1 and 2.

Step 4: The instproc unknown of class SplitObject

SplitObject is the uppermost class of every TclObject classes--meaning every TclObject must derive from this class. It defines instproc unknown as follows (see file ns-allinone-xx/tclcl-x.xx/tcl-object.tcl for more detail):

SplitObject instproc unknown args {
    if [catch "$self cmd $args" ret] {
        set cls [$self info class]
        global errorInfo
        set savedInfo $errorInfo
        error "error when calling class $cls: $args" $savedInfo
    }
    return $ret
}

This instproc is in fact bound to the C++ domain. We shall talk about it in details in the next post. Please stay tune!!
======================================================
T. Issaraiyakul and E. Hossain, “Introduction to Network Simulator NS2”, Springer 2009. Buy it now from

You may also find lecture notes and other resource at the following website: http://www.ece.ubc.ca/~teerawat/NS2.htm

Are we a better guesser than a mouse?

2010-07-17T04:47:00.002-06:00

<p>&amp;amp;amp;lt;p&amp;amp;amp;gt;&amp;amp;amp;amp;amp;amp;amp;amp;lt;p&amp;amp;amp;amp;amp;amp;amp;amp;gt;&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;a href="http://www.amazon.com/dp/0307275175?tag=ns2ultteeiss-20&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;camp=213761&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;creative=393545&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;linkCode=bpl&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;creativeASIN=0307275175&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;adid=17JYG930T2D4RC9VYBDZ&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;"&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;http://www.amazon.com/dp/0307275175?tag=ns2ultteeiss-20&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;camp=213761&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;creative=393545&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;linkCode=bpl&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;creativeASIN=0307275175&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;adid=17JYG930T2D4RC9VYBDZ&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;/a&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;&amp;amp;amp;amp;amp;amp;amp;amp;lt;/p&amp;amp;amp;amp;amp;amp;amp;amp;gt;&amp;amp;amp;lt;/p&amp;amp;amp;gt;</p>It is compelling to answer ‘yes’. Unfortunately, the answer is ‘not always’. To see why, let’s setup an experiment where red and green cards are shown to a test subject. The job of the subject is to observe a sequence of cards and to guess the color of the next cards. Suppose that we use a certain sequence where 75% of the cards are green and 25% are red cards. The subject might choose to use one of the following 2 strategies for guessing:

(i) Probability based guessing: Observe and compute probability of cards being green and red. Then always choose the color with higher probability. In the above example, the subject will always choose green. If we let the subject keeps guessing, the correct probability will approach 75%. But it can never be better than 75%. This is what most non-human animals such as mouses would do.

(ii) Pattern matching: Try to figure out the pattern, and guess accordingly. Suppose the sequence is 3 green card followed by 1 red card. Once you figure out the pattern, you will always guess correctly.

Human is not very good at computing probability on the fly. So we usually resort to pattern matching. If we can recognize the pattern, we will do very good at predicting the color. But if the pattern is totally random with the ratio 3 out of 4 being green, there will be no pattern. We can guess nothing, and we will be outperformed by mouses.

Source: The Drunkard's Walk: How Randomness Rules Our Lives by Leonard Mlodinow, Chapter 1 [Read the Book Review] [Read the Next Part].

---------------------------------------------------------------------------------------------------------
Book or Audiobooks?

C++ and OTcl Linkage: OTcl Commands — Getting Started

2010-07-12T02:28:00.000-06:00

Note: The content in this series is extracted from the book, Introduction to Network Simulator NS2. You may have to read chapter 3 of the book for better understanding.
OTcl Command -- Getting Started

View more presentations from Teerawat Issariyakul.

Introduction

This post is the second post in the series on C++ and OTcl Linkage:

   1. Why Two Languages?
   2. Binding C++ and OTcl classes [Main steps, The mechanism].
   3. Variable binding
   4. OTcl command: Invoking C++ statements from the OTcl domain [ Getting Started, Make it more Interesting ]
   5. Eval and result: Invoking OTcl statements from the C++ domain
   6. Object binding and object construction process.

In the previous post, I blogged about how C++ and OTcl classes are bound together. In this post, I will explain how to bind C++ and OTcl class variable together.
=======================================================
T. Issaraiyakul and E. Hossain, “Introduction to Network Simulator NS2”, Springer 2009. Buy it now from

You may also find lecture notes and other resource at the following website: http://www.ece.ubc.ca/~teerawat/NS2.htm

Segmentation Fault: A Common Error in NS2

2010-07-08T21:16:00.001-06:00

Introduction

One of the most common error you might have found when running NS2 is "Segmentation Fault". This is just a type of runtime error. If you run, the same program in Win32 console application, Windows will show a run-time error message and terminate the program. So don't be intimidated by it.
Example

Example of codes which causes segmentation fault is shown below:

int x[10];
x[20] = 0;

where you create an array x with 10 slots, but try to access 20th slot of x.

Suggestion?

Cause 1 (C++): Most segmentation fault errors are usually rooted in C++ domain. So, check your C++ codes. I can't help finding bugs in your codes. But, here is the guideline for debugging:

Think carefully you have done before you see segmentation fault. The part which causes error is likely to be in that part.
If you do not find error, go back even further. Try to remove as many new modules that you have added as you can. Do it until you no longer see segmentation fault. Then start adding your module one by one until you see segmentation fault again. The most recently added module is the module which is most likely to cause the problem.
If you still do not find the error, you might have to reinstall NS2 and slowly added your modules one by one again. Use approach similar to step 2.

I know debugging is a boring and laborious job. But you've gotta do it to move on. Just don't give up.

Cause 2 (Misconfiuration in OTcl): Another common cause is in OTcl, where you do not attach NS2 components correctly. An example is that you may set the target of a link to an object which does not exist. So fix it!!

Note: The point where error occurs is still in C++, but it is caused by misconfiguration in OTcl.

========================================================

For more information about randomized scenarios, see Chapter 12 in the following book from Springer:
T. Issaraiyakul and E. Hossain, “Introduction to Network Simulator NS2”, Springer 2009. You may also find lecture notes and other resource at the following website: http://www.ece.ubc.ca/~teerawat/NS2.htm

C++ and OTcl Linkage: Binding variables

2010-07-05T20:19:00.000-06:00

[ns2] C++ Command assert()

2010-06-30T23:09:00.000-06:00

When delving into the C++ domain in NS2, you would be likely to find a C++ statement assert(<expr>). For example, in file ~ns/common/agent.cc,

assert(p!=NULL)

This function inspects its input argument <expr>. If the <expr> is

TRUE, it does nothing.
FALSE, it terminates the program.

For more information, please see [ this link ].

C++ and OTcl Linkage: Binding C++ and OTcl classes — Part II

2010-06-20T20:56:00.000-06:00

C++ class name = MyObject
OTcl class name = MyOTclObject

The main step in doing so was to add the following code in a C++ file otcl.cc:
1 #include "otcl.h"
2 static class MyObjectClass : public TclClass {
3 public:
4    MyObjectClass() : TclClass("MyOTclObject") {}
5    TclObject* create(int, const char*const*) {
6       return (new MyObject());
7 }
8 } class_my_object;

In this post, we are going see what the above codes mean.

It's Just Declaration of a Variable
The above codes look quite scary. But it is quite simple. Let us go step by step, shall we?

I. We can declare a static C++ variable class_my_object whose class is MyObjectClass as follows.

static MyObjectClass class_my_object;

II. Now, class MyObjectClass has not been declared. We need to insert class definition before the variable declaration. The code would look like this.

static class MyObjectClass : public TclClass {
<CLASS DEFITION>
} class_my_object;
which says that class MyObjectClass derives from class TclClass.

Class Definition

There are 2 main steps in class definition
1. Class constructor (Line 4)
MyObjectClass() : TclClass("MyOTclObject") {}
which feeds the OTcl class name MyOTclObject to the based class TclClass.
2. Function create(...) (Lines 4-7)

This function is invoked when a MyOTclObject object is created in the OTcl domain using the following statement
new MyOTclObject
What function create(...) does is to create and return a C++ object, namely MyObject, to the caller (Line 6).

Wrap-up
So the above chunk of codes is just declaration of a class and a static variable which maps a C++ class MyObject to an OTcl class MyOTclObject.
When an OTcl object is created, NS2 looks up the repository of mapping variables, and calls function creates(...) in order to create a shadow C++ object. I will blog about the object creation process again later in this series.
=======================================================
T. Issaraiyakul and E. Hossain, “Introduction to Network Simulator NS2”, Springer 2009.

You may also find lecture notes and other resource at the following website: http://www.ece.ubc.ca/~teerawat/NS2.htm

[BookReview] The Reader by Bernhard Schlink

2010-06-16T21:57:00.000-06:00

Rating: 3/5
Genre: Novel

Book Review
I picked this book by the recommendation from one of my friends. She told me that it was a good story, only if you don’t know the story before I read it, and it was.

This story is translated from A Germany novel, “Der Vorleser”. It is the story during the Holocaust, told by the main character Michael Berg. Most of the storytelling is engaging, but some parts are not. The more exciting part is the place where the book surprises me. I won’t spoil you with what that is. You have to read the book.

Overall, I think this is a good book. It worthes my time reading this book.

Quotes

"But at a certain point the memory of her stopped accompanying me wherever I went. She stayed behind, the way a city stays behind as a train pulls out of the station. Its there, somewhere behind you, and you could go back and make sure of it. But why should you?"

"So I was still guilty. And if I was not guilty because one cannot be guilty of betraying a criminal, then I was guilty of having loved a criminal."

"This is what must happen to old married couples, I thought: the young man is preserved in the old one for her, the beauty and grace of the young woman stay fresh in the old one for him."

---------------------------------------------------------------------------------------------------------
Book or Audiobooks?

There is one more reason that may encourage you to go for the audiobook version. You can get it now for FREE. Audible offers you a free trial for 14 days. Even if you get the book and cancel the subscription right away (so that you don't have to pay), you can keep the book. And, don't worry if you lost the audiobook file. Just log into audible.com. You can keep downloading the over and over again.

About the summary: It takes time to finish up a book. And, when you do, sometimes, you want to review what you learn from the book. If you do not make notes as you read, you might have to go through the book once again. This can be time-consuming when you are dealing with a book. But you can still flip through the book and locate what you are looking for.

However, when the material is an audiobook, it is extremely hard to locate a specific part of content. Most likely you will have to listen to the entire audiobook once again.

This book summary will help solve the pain of having to go through the book all over again.

I am leaving out the details of the books. Most books have interesting examples and case studies, not included here. Reading the original book would be much more entertaining and enlightening. If you like the summary, you may want to get the original from the source below.

C++ and OTcl Linkage: Binding C++ and OTcl classes -- Part I

2010-06-12T02:29:00.000-06:00

Note: The content in this series is extracted from the book, Introduction to Network Simulator NS2. You may have to read chapter 3 of the book for better understanding.

Introduction

This post is the second post in the series on C++ and OTcl Linkage:

   1. Why Two Languages?
   2. Binding C++ and OTcl classes [Main steps, The mechanism].
   3. Variable binding
   4. OTcl command: Invoking C++ statements from the OTcl domain
   5. Eval and result: Invoking OTcl statements from the C++ domain
   6. Object binding and object construction process.

In the previous post, I blogged about the motivation of having 2 languages. In this post, I will show you how to bind a C++ class to an OTcl class so that when an OTcl object is created, a shadowed C++ object is automatically crated.
Explanation by Examples

Here is what I would do in this post:

Suppose I have a C++ class "MyObject" and an OTcl class "MyOTclObject".
I would like to bind these two classes together so that when I call

new MyOTclObject

from the OTcl domain, a shadow C++ object is automatically created.

Key Steps

I. Create a C++ class "MyObject".
II. Bind two class names "MyObject" and "MyOTclObject" together.
III. Incorporate the classes into NS2 using the Make utility.
IV. Test.

Note that all these steps are done in 2 files: otcl.h and otcl.cc

Step I: Create a C++ class "MyObject".

You can do so by defining the new class in the file otcl.h

#include "object.h"
class MyObject : public TclObject {
public:
MyObject();
virtual ~MyObject(){};
};

Step II: Bind two class names "MyObject" and "MyOTclObject" together.

Here is the detail in the file otcl.cc.

#include "otcl.h"
static class MyObjectClass : public TclClass {
public:
    MyObjectClass() : TclClass("MyOTclObject") {}
    TclObject* create(int, const char*const*) {
        return (new MyObject());
    }
} class_my_object;
I will explain the details in the next post.

Step III. Incorporate the classes into NS2 using the Make utility

Make change to the file ~ns/Makefile. Look for the following section beginning with

OBJ_CC = \
    tools/random.o \
    ...

Then add the following line to the end of this section

<YOUR_DIR>/ otcl.o

Do not forget to put '\' between two lines.

Then at command prompt, run

>> make

The new classes MyObject and MyOTclObject should be incorporated into NS2.

Step IV. Test

One last thing that we should do is to test whether what we did works. So just run NS2, and you should see the following results.

>> ns
% new MyOTclObject
_o4
%

which means an OTcl object _o4 was created.
Summary
So if you would like to bind C++ and OTcl classes, you can just copy the following code and put the class name in the relevant place.

static class <ANY CLASS NAME> : public TclClass {
public:
    MyObjectClass() : TclClass("<YOUR OTCL CLASSNAME>") {}
    TclObject* create(int, const char*const*) {
        return (new <YOUR c++ CLASSNAME>());
    }
} <ANY OBJ NAME>;

Wrap-Up

That's it! It is not that hard to bind a C++ class to an OTcl class, right? In fact, this process is used repeatedly in NS2. Look for example at

- C++ class DropTail, which is bound to OTcl class Queue/DropTail in file ~ns/queue/droptail.cc
- C++ class Connector, which is bound to OTcl class Connector in file ~ns/common/connector.cc
- C++ class TcpAgent, which is bound to OTcl class Agent/TCP in file ~ns/tcp/tcp.cc

Although the key step are quite straightforward, the process is interesting. I will blog about the process later in the next post. Stay tune!
=======================================================
T. Issaraiyakul and E. Hossain, “Introduction to Network Simulator NS2”, Springer 2009.

You may also find lecture notes and other resource at the following website: http://www.ece.ubc.ca/~teerawat/NS2.htm

The Responsible Free Market Economy -- The Leader's Way, Chapter 9

2010-06-10T10:29:00.002-06:00

Socialism and Capitalism

Socialism is a great concept. Conceptual, it should bring benefits to all and eliminate poverty. But in practice, power in socialistic society tends to be in the hand of a group of few people. Most people work very hard, but gain very little. Lacking motivation, socialistic economy tends to be stagnant. Although socialism focuses on the distribution of wealth, there is no wealth to distribute.

Capitalism, on the other hand, promotes competition in a free market. Freedom breeds competition. Free and fair competition leads to creation and wealth. Capitalism focuses on creation of wealth, not the distribution of wealth. Therefore, rich people become richer, while the poor remains poor.

Responsible Free Market Economy

In a free market, the roles of government are to

Establish infrastructure necessary for fair competition.
Development of property rights
Bring in justice

From time to time, companies tend to form a group to collude in fixing product price, removing supply from the market, pressuring the government create regulation which prevents fair competition. The government should try to resist the pressure and set things right.

Although the government play a major role in distributing well being to its citizen, we cannot entirely rely on the government.

"It is impossible for the government to make people behave decently by law. The system will only work well when the leader in business and government have right motivation and act accordingly."

Given more freedom, the companies just have to act more responsibly.

Source: THE Leader's Way: Business, Buddhism and happiness in an interconnected world by His Holyiness The Dalai Lama and Laurens Van Den Muyzenberg, Chapter 9 [Read the Book Review] [Read the Next Part].
---------------------------------------------------------------------------------------------------------
Book or Audiobooks?

Error message: Undefined reference to vtable

2010-06-08T05:38:00.000-06:00

Introduction
Another common error message when you compile NS2 would look like this

Book/otcl.o:otcl.cc:(.text+0x8c): undefined reference to `vtable for MyObject'
collect2: ld returned 1 exit status
make: *** [libns.dll] Error 1

Why?
This error is caused by declaring but not implementing one or more virtual function.

How to Fixed It?
Provide implementation to all virtual functions

Details
The above is all you need to know to fix it. But if you want to understand more, read on.

What is vtable?

From [this Wikipedia], vtable is known by several names, including a virtual method table, virtual function table, and dispatch table. It is a mechanism to implement run-time method binding (a.k.a. dynamic dispatch). A lot of buzz words, eh? Well, let's boil them down to plain English, shall we?

Polymorphism

Polymorphism is the ability of C++ to invoke the same function with different implementation under different context. Difficult to understand, right? So let's look at an example:

Example: Classifiers

Consider two main packet classifiers [Read more about classifiers here]:

Address classifiers: Select and send packet to the next NsObject based on the address.
Port classifiers: Select and send packet to the next NsObject based on the transport layer port.

The job description of both the classifiers is the same: To classifier and forward packets. The difference is how they classify the packets.

Polymorphism for Classifiers

Polymorphism defines a function classify(p) in class Classifier, and let the derived class defined their own way to classify packets. Usually, programmers would work with Classifier in their program. At run-time, the users chooses the classifier types (i.e., either address or port) based on their need, and instantiate objects accordingly. At the instantiation, objects morph (transform) itself from Classifier to either address classifier or port classifier.

So Where is Vtable?

Under the polymorphism concept, we need a mechanism to tell the program which implementation function classify(p) should use: Inspecting the address or inspecting the transport layer port. In C++, such the mechanism is vtable. Vtable stores the address which contains function implementation of each object. When a function is invoked, C++ identifies the object, and fetches the relevant implementation by looking at vtable.

About the Error

It should now be clear that if you do not provide implementation for virtual functions, C++ cannot construct vtable. Therefore, it shows the above error message on the screen.

A Common Error

Destructor is declared as virtual in class TclObject, which is the base class for almost every class in NS2. In your new class, you have few choices

Do not declare the destructor. In this case, the destructor of class TclObject will be used.
If you declare the destructor, you MUST provide the implementation, even if it is an empty implementation (i.e., {}). Otherwise, you will see the above error message.

=======================================================
T. Issaraiyakul and E. Hossain, “Introduction to Network Simulator NS2”, Springer 2009.
You may also find lecture notes and other resource at the following website: http://www.ece.ubc.ca/~teerawat/NS2.htm

C++ and OTcl Linkage: Why Two Languages?

2010-05-31T06:23:00.001-06:00

Note: The content in this series is extracted from the book, Introduction to Network Simulator NS2. You may have to read chapter 3 of the book for better understanding.

Introduction

NS2 consists mainly of two languages: C++ and OTcl. Each of these two languages has its own strengths and weaknesses. NS2 beautifully integrates these two languages to draw out their strengths. For most of the time, you would not need to know the integration mechanism. But you need to know the strength and weaknesses of these two languages in order to apply them properly.

Strengths and Weaknesses of C++ and OTcl

C++: C++ is a compiled programming language. A C++ program needs to be compiled (i.e., translated) into the executable machine code. Since the executable is in the form of machine code, C++ program is very fast to run. However, the compilation process can be quite annoying. Every tiny little change like adding "int x = 0;" will take few seconds.
OTcl: OTcl is an interpreted programming language. An OTcl program can run on the fly without the need for compilation. Upon execution, the interpreter translates OTcl instructions to machine code understandable to the operating system line by lin. Therefore, OTcl codes run more slowly than C++ codes do. The upside of OTcl codes is that every change takes effect immediately.

NS2 documentation suggests that C++ is slow to change but fast to run. OTcl is slow to run but fast to change.

Three Programming Style

In order to understand the need of having two languages, let's look at what a C++ programmers would do. Suppose, we program C++ codes in file prog.cc and prog.h. We will need to create an executable file prog.exe. Here are three programing styles:

1. Basic C++ Programming

With this style, you write C++ codes, compile them, and run the executable file. This is quite easy, and is what most programmers would do for small and simple tasks.

But again, as the program gets bigger, you will need to compile the program for every little change. This programming style lacks flexibility.

2. C++ Programming with Input Arguments

C++ allows programmers to supply input arguments: argc (number of input arguments) and argv (vector or array of input arguments).
Suppose you would like to simulate a network with n nodes fully connected with link speed s Mbps. With the first programming style, you will need to recompile the code every time you change the speed and/or the number of nodes.

With the use of input arguments, you may write a program to take the number of nodes and link speed as the first and second input arguments, respectively. You C++ file would look something like this.

#include<iostream>
using namespace std;
void main(int argc, char* argv[]){
cout<< "The number of node is " <<argv[0]<<endl;
cout<< "Speed of all links is " <<argv[1]<<endl;
}

The resulting executable program would have the following syntax.

prog <num_node> <link_speed>

For example, if you would like to have 10 nodes each connected with 3 Mbps links, you would run

prog 10 3

This style gives the users flexibility to change system parameters without compilation.

3. C++ Programming with a Configuration File

The problem with the second style is that the invocation can get quite messy as the number of input arguments increases. Imagine a scenario with 10 nodes whose connecting links have various speed. It would be quite difficult to input say different sets of 20 parameters for each run.

The third programming style improves the second one by specifying all the parameters in one file called "configuration file". Basically, it is the second style with the name of the configuration file as its only input parameter. The details of link speed, number of nodes, the topology, and so on, can be specify in the configuration file.

What about NS2?

As you might imagine, NS2 uses the last style, where the configuration file is an OTcl file called "Tcl Simulation Script". This file contains information about what you would like to simulate such as "set ns [new Simulator]", "set n0 [$ns node]", and so on. This Tcl simulation script is just the input configuration file to a C++ program, "~ns-2.35/ns.exe"

If you have a configuration file "simple.tcl", you can run NS2 by executing

ns simple.tcl

where ns is the executable program obtained from compiling the entire NS2 codes using "make" utility [see this link for details], and simple.tcl is an input configuration file of the executable file ns.

So Which on Should I Look into? C++ or OTcl?

Perhaps, this is the question you most want to ask. The above provide the motivation of having two languages. The guideline of selecting the language is provided below:

OTcl is a language for creating a network so that you don't have to recompile the codes every time you make changes to your simulation scenarios. It is also used to connect blocks (e.g., classifier, links, agent) within each NS2 components (e.g., node).
C++ defines internal mechanism of each block. It does things like packet forwarding, scheduling events, collecting statistic, and so on.

According to the OOP concept, every component should be self-contained and should provide interface to talk to other components. C++ is an OOP. Therefore, it defines these OOP functionalities.

What missing is how the components are linked together. YOU, as a programmer, should be the one who decide what NS2 components are needed and how they are linked together (e.g., Node 1 to Node 3). And, you would tell NS2 to do so (i.e., linking components) by using OTcl.

Summary

By now, you should know what NS2 have two languages. But if you don't or if you think it's too much to remember, just read the following. These two points are the summary of the above.

Use C++ for internal mechanism.
Use OTcl for configuration.

=======================================================
For more information about C++ and OTcl linkage see Chapter 3 in the following book from Springer:
T. Issaraiyakul and E. Hossain, “Introduction to Network Simulator NS2”, Springer 2009.

You may also find lecture notes and other resource at the following website: http://www.ece.ubc.ca/~teerawat/NS2.htm

Entrepreneurship and Poverty -- The Leader's Way, Chapter 8

2010-05-29T13:00:00.003-06:00

"Poverty is a problem of the mind, not the lack of resources or the lack of intelligence of the people."

In order to improve poverty,

Government must be motivated to help.
Economy system must be a responsible one.
Regulation must stimulate entrepreneurship
Fair banking, property right, and family planning must be in place.

Poverty usually congregates around the poor. These people need to spend less, leading to stagnant economy and more unemployment. The government
needs to promote entrepreneurship among the poor. This will alleviate poverty
and increase liquidity.

Poor people do not lack skill. They lack opportunities. In fact, they are willing to work harder than the wealthy.

Micro-credit lending is one of the concepts whose goal is not to seek benefit, but to provide opportunities to the poor. It focuses on trust rather than on collateral contracts.

“Freedom without responsibility is not acceptable. It is even dangerous.”

Source: THE Leader's Way: Business, Buddhism and happiness in an interconnected world by His Holyiness The Dalai Lama and Laurens Van Den Muyzenberg, Chapter 8 [Read the Book Review] [Read the Last Part].
---------------------------------------------------------------------------------------------------------
Book or Audiobooks?

C++ and OTcl Linkage

2010-05-25T08:03:00.000-06:00

Note: The content in this series is extracted from the book, Introduction to Network Simulator NS2. You may have to read chapter 3 of the book for better understanding.

Introduction

NS2 consists of two languages: C++ and OTcl. For most of the time, you would configure (e.g., "$ns duplex-link ... ", "$ns attach-agent ...") a network in OTcl. But the real simulation is running in C++. If you are having troubles grasping the concepts of the linkage, stick around. I hope I can help enlighten you guys :)

Outline

Here is the outline of this series.

Why Two Languages?
Creating C++ and OTcl classes.
Class Binding
Variable binding
OTcl command: Invoking C++ statements from the OTcl domain
Eval and result: Invoking OTcl statements from the C++ domain
Object binding and object construction process.

Do you like it?

I believe the above are all you need to understand the binding process. If you like it, please stick around and perhaps tell your friends about it. I will blog about them one by one. If you have any comments or suggestions, please place them on my facebook fan page [ click here ].
=======================================================
For more information about C++ and OTcl linkage see Chapter 3 in the following book from Springer:
T. Issaraiyakul and E. Hossain, “Introduction to Network Simulator NS2”, Springer 2009.

You may also find lecture notes and other resource at the following website: http://www.ece.ubc.ca/~teerawat/NS2.htm

The Challenge of Globalization -- The Leader's Way, Chapter 7

2010-05-20T10:27:00.003-06:00

Globalization business model

Globalization has led the business through 3 following stages

Import/Export: Focus on trading on raw material and production
Satellites: All the branches take the commands from the headquarter. Build branches on several countries to

Avoid importing/exporting raw material
Understand local people better
Avoid import/export regulation

Globally integrated: This stage is similar to the satellite model. The difference is that the business initiative can come from any country (not just the headquarter country).

Globally integrated companies are both less and more vulnerable at the same time. It is less vulnerable, since a failure to execute in one country does not result in the collapse of the company. The company still operates in other countries. It is more vulnerable due to increasing more level of trust among all the local branches. An execution failure or bad reputation in one country will impact the company more greatly.

The Role of Globally Integrated Company

Globalization was seen as an exploit over poor countries. But it is in fact a change which occurs much faster than before, and poor countries simply cannot keep up with. In fact, globally integrated companies can greatly contribute to people's well being, if they act responsibly. They can help underdeveloped countries catch up with developed countries, and help alleviate environmental problems.

Globalization and Competition

Conceptually, globalization breeds competition, which should lead to benefit for all (e.g., good products at reasonable price). Competition should be a mean which takes us to the happy ending. Unfortunately, in reality, there are several bad practices which prevent us from such the happy ending.

Obvious bad practices are for example selling bad products and services, irresponsibly dumping waste in the ocean, and so on. Apart from these obvious bad practices, the hidden ones are monopoly, price fixing, and corruption. The government should step in to help alleviate these hidden bad practices and promote fair competition.

Globalization and Innovation

Innovation has become global in two ways. First, when a new product comes into the market, it is available globally. Secondly, innovation depends on diversity. The invention is more likely when involving various kinds of people.

Source: THE Leader's Way: Business, Buddhism and happiness in an interconnected world by His Holyiness The Dalai Lama and Laurens Van Den Muyzenberg, Chapter 7 [Read the Book Review] [Read the Next Part].
---------------------------------------------------------------------------------------------------------
Book or Audiobooks?

Classifiers and Routing Module: Attaching Agents

2010-05-18T00:24:00.001-06:00

Note: This is a detailed note for the book, Introduction to Network Simulator NS2. You may have to read chapter 6 of the book for better understanding.

Introduction

This post is a sequel of the previous post, which demonstrated the relationship of classifiers, routing modules, and nodes:

What’s in This Post
So far, what we have looks like the figure below.

This post will show you how to put yellows box, port classifier and agents, to a node.

Routing and Transport Layer Bridge in a Computer

When a packet arrives your computer, your computer will check the IP address. If the IP Address is for itself, it will deliver the packet to the attach transport layer protocol (e.g., your web browser may use TCP port 49175). Otherwise, it will forward the packet according to the routing table.

Note: In windows, you can use the command

route print

to show routing table. Here is the example result.

Also, you can use the command

netstat -an

to show the transport layer port. Here is the example result.

What about NS2

Again, in NS2, a node can be a router or a computer. But it doesn't matter which one you are considering. NS2 makes no difference between these two types. A node is able to forward packets based on destination address and transport layer port indicated in the packet header.

NS2 uses class Agent as a transport layer protocol (In fact, class Agent is used to create and destroy packets, but we'll talk about that later). So, our objective is to

1. Create agents $a0 by using

>> set $a0 [new Agent/TCP]

2. Attach the created agent to the node $n0 by using

>> $ns attach-agent $n0 $a0

It is the latter step which is a bit complicated. So I better explain.

Key steps.

So I am going to use the previous notation. Please see [ here ] before proceeding.

I. [Tclscript] $ns attach-agent $n0 $a0

II. [f_LT] Simulator::attach-agent{ node agent }
-> [1] $node attach $agent: [see step III.]

III. [f_NT] Node::attach { agent { port "" } }
-> [1] set dmux_ [ new classifier/Port ]: Create a port classifier
-> [2] $self add-route $address_ $dmux_: [see Step IV]
-> [3] set port [ $dmux alloc-port [ [ Simulator instance ] nullagent ] ]:
     -> [3.1] [ Simulator instance ] nullagent ] returns the null agent which is used to destroy packets
     -> [3.2] $dmux alloc-port [...]:
        - Store the agent from III.3.1 in the next available slot of the classifier $dmux
        - Return the associated port (or slot) number.
        - Note: In port classifiers, the slot number is the same as the port number
        - For more information about classifier, plese see [this link]
    -> [3.3] $port [...] stores the value returns from III.3.2 in a local variable $port
-> [4] $agent set agent_port_ $port: Store the allocate port number $port into the instvar $agent_port_ of the input $agent
-> [5] $self add-target $agent $port: Tell the Node that the $agent is attached to port number $port [see Step V]

IV. [f_NT] Node::add-route { dst target } (from III.2)
-> $rtnotif_ add-route $dst $target: From the above figure, $rtnotif_ is a routing module responsible for packet routing. In this particular context, $dst is the node address and $target is $dmux_ (see III.2). Therefore, this statement tells $rtnotif_ that any packet destined to the current node should be forwarded to $dmux_. Again, we do not configures classifiers directly. Routing module is the single point of classifier management, and we shall configure classifiers through routing modules only. For more information, please read [ this link ].

V. [f_NT] Node::add-target { agent port } (from III.2)
-> Similar to add-route, instproc add-target tells the node that packet whose port is $port should be forwarded to the agent $agent.

The job of classifying and forwarding packets based on the transport layer port is attributed to port classifier, which NS2 calls a "demultiplexer". Again, we do not configure the demultiplexer directly but does so through a routing module $ptnotif_

As show in [ this link ], $ptnotif_ has different implementation than $rtnotif_. It is based on list (i.e., array), not pointers. So what you see in this step is

foreach m [ $self set ptnotif_ ] {
      $m attach $agent $port [see Step VI]
}

VI. [f_RT] RtModule::attach { agent port } (From Step V)
-> [1 (Sending Agent)] $agent target [ [ $self node ] entry ]
     A sending agent creates a packet and sends the created packets to the node. Then the node looks at the destination address in the packet header and forward the packet accordingly.
     [ [ $self node ] entry ] return the entry point of the node associated with the routing module under consideration
     So the entire statement says that "set the target of the agent to be the node entry". The node will later pass it to its address classifier during normal packet forwarding mechanism.

-> [2 (Receiving Agent)] [ [ $self node ] dmux ] install $port $agent
If $agent is a receiving agent, the packet will come from the node, pass through the address classifier and the demultiplexer, and arrive $agent.

What we have to do here is to configure the demultiplexer obtained from [ [ $self node ] dmux ]. The entire statement installs $agent in the slot number "$port" of the demultiplexer. (For the detail of object installation in a classifier please see [this link] ).

Wrap-Up

Long, isn't it. Well, it's quite complicated. But that's how it works in NS2. For now, I think it is quite enough for you to get yourself working in an NS2 node. Next time you'd like to have a node classify packets based on your own criteria, follow the instruction in this series. That way you can make your NS2 code neat and compatible.
I do left out the details of route configuration. It is quite similar to agent attachment. You can research about it yourself. But if you'd like me to talk about it. Please let me know.
Comments? Facebook post? Please let me know. I appreciate the comments or questions you all have.

==============================================================

For more information about NS2, see Chapter 6 in the following book from Springer:
T. Issaraiyakul and E. Hossain, “Introduction to Network Simulator NS2”, Springer 2009.

You may also find lecture notes and other resource at the following website: http://www.ece.ubc.ca/~teerawat/NS2.htm

Doing Business Right -- The Leader's Way, Chapter 6

2010-05-15T10:24:00.001-06:00

Doing business right means doing business with warm hearts--meaning thinking of others' feeling. Although profit is essential, money can't buy happiness. Companies which do business right will attract consumers, investors, and employees. After all, people want to be a part of something they can be proud of.

Negative Factors

The following are negative factors which contribute to corporate bad reputation:

Leaders without humility (Flashy leaders tend to be self-interest and lead the company into great risks).
Creative or fraudulent accounting
Increasing disparity in compensation
Exploited practices
Marketing of harmful product
Human right and environment violation
Countries without good governance

Credible Corporation

Promotes corporation citizenship: A corporate can be viewed as a member of the society. As a good citizen, it should practice right view and right conduct such as Corporate Social Responsibility (CSR) and Environmental Impact Assessment (EIA) programs.
Accepts the honesty and success can go exist. The old business model is based on win or lose. There is no room for honesty. As people become more civilized, honesty has started to gain traction. An example is the magazine Ethisphere publishes the name of most ethical corporations in the world.

"While good sciences and regulation approval are essential, they are not sufficient. We need to engage with society, understanding and responding to people's concern and expectation'' -- James Smith, Shell U.K.'s country chairman.

NGOs

NGO lives for general public, and discovers bad deeds that some companies try to hide. This is not the case for the companies with right conducts. They have got nothing to hide. Instead of trying to deny NGO, they can get help from NGO, since most people tend to believe NGOs more than the company. For example, if a company wants to open a factory in a certain country, it can ask NGO to study the possibilities, and cultural issues that might arise.

Source: THE Leader's Way: Business, Buddhism and happiness in an interconnected world by His Holyiness The Dalai Lama and Laurens Van Den Muyzenberg, Chapter 6 [Read the Book Review] [Read the Next Part].
---------------------------------------------------------------------------------------------------------
Book or Audiobooks?

Creating Profit, Jobsor Happiness? -- The Leader's Way, Chapter 5

2010-05-13T05:31:00.001-06:00

An organization is the place where people congregate. These people need common purposes and spontaneous leader.

"Any organization is both more and less than the sum of its members. It is less because the members of the group devote only a part of their time to the organization, and much more because the organization as a whole can accomplish tasks the individual members cannot succeed in carrying out on their own.''

A Living Entity

We can consider business as a living entity. If food is essential to life, profit is essential to business. Business can be motivated. It can thrives, withers, and renews itself. It can act responsibly or irresponsibly.

As people should not live to eat, business should not live to make profit only. Making less profit is similar to having less food to eat. But that's not necessarily a bad thing. Business has three important purposes: 1) Create profit, 2) serve the customers, 3) act responsibly.

Three groups of people

People have two eyes. One eye is for working. The other sees morality. Based on they eyes, people can be classified into:

The blinds: These people have no vision. They do not work. They cannot differentiate between vulgar and fine. As as result, they live in a poor life. They might behave badly (e.g., steal, rob, deceive) to earn wealth just to live.
The one-eyes: Although these people have vision and work hard to gain wealth. They do not act morally. They may acquire their wealth in a wrong way.
The two-eyes: These have vision to gain wealth, and they acquire their wealth righteously. They know what is good, what is evil.

One should avoid the blinds and the one-eyes, and associate with the two-eyes.

Satisfaction and Happiness

"Happiness depends on satisfying different needs. But some fundamental need has to be satisfied before. Others can be considered.''

There are 5 levels of satisfaction.

Physical need
Safety and Security
Love and Belongingness
Self-esteem
Self-actualization, vitality, creativity, self-sufficiency, authenticity, playfulness, and meaningfulness

The lower level (lower number) must be satisfied before considering the higher level. For example, people need to earn enough money for food, shelter, and so on. Given the basic satisfaction, people look for other satisfaction. For example, they want to be a part of the company they can be proud of.

Source: THE Leader's Way: Business, Buddhism and happiness in an interconnected world by His Holyiness The Dalai Lama and Laurens Van Den Muyzenberg, Chapter 5 [Read the Book Review] [Read the Next Part].

---------------------------------------------------------------------------------------------------------

Book or Audiobooks?

About the summary: It takes time to finish up a book. And, when you do, sometimes, you want to review what you learn from the book. If you do not make notes as you read, you might have to go through the book once again. This can be time-consuming when you are dealing with a book. But you can still flip through the book and locate what you are looking for

However, when the material is an audiobook, it is extremely hard to locate a specific part of content. Most likely you will have to listen to the entire audiobook once again.

This book summary will help solve the pain of having to go through the book all over again.

I am leaving out the details of the books. Most books have interesting examples and case studies, not included here. Reading the original book would be much more entertaining and enlightening. If you like the summary, you may want to get the original from the source below.

[ns2] Classifiers and Routing Modules: Implemenation of Routing Module--rtnotif_ v.s. ptnotif_

2010-05-10T00:18:00.000-06:00

What’s in This Post

Before proceeding further, let me refresh you memory a bit. This is the Node architecture we see earlier. We know that $rtnotif_ is bound to address classifiers and ptnotif_ is bound to port classifiers.

This post focuses on how exactly NS2 implement $rtnotif_ and $ptnotif_

What are the purposes of routing module again?

A classifier is a multi-target forwarder [see this post] usually stored in a Node. There can be more than one classifiers in a Node, since a Node may have several criteria to classify packet (e.g., based on address, port, flow, priority).

Configuration of classifiers can be a mess. If you have 20 classifiers, you can have to have 20 configuration statements at a time. Keeping tracks of these 20 classifiers can be a headache. So, why don't you create groups of classifiers, and configure the groups instead of configuring each classifier individually? NS2 calls these groups "routing modules".

The Concept of Routing Modules

Conceptually, you create and associate a classifier with a routing module. And, you create a group by linking related routing module together. When you need to configure classifier, you do so through the "head" of the group (of routing modules) only.

Two Main Types of Implementation: Link-list and Array

There are two common ways to create a group of routing modules

1. Link-list based.

This approach is used for a group of address classifiers in a node. An example configuration is shown below:

From the above figure, a routing module connects to a classifier using its pointer classifier_. They are are links together by using pointer "next_rtm_". When we need to add a routing entry to all classifiers (by calling the instproc add-route), we only need to send the command through the first routing module (RM1), and the chain of routing modules will automatically propagate the commend to all connecting classifiers.

Note: Usually, a Node stores the first (i.e., head) routing module for the address classifier group in its instvar $rtnotif_

2. Array (list) based.

This approach is used for a group of port classifiers in a node. An example configuration is shown below:

Similar to the address classifier group, each routing module in the port classifier group connects to a classifier using its pointer classifier_.

From the above figure, routing modules are stored in each component of a array variable. Again, we do not attach an agent directly to each of port classifiers. But we do so through the instvar storing the routing modules associated to all port classifiers (by calling the instproc add-target). NS2 will automatically send agent attaching command to all routing module in the array variable.

Note: Usually, a Node stores all routing modules for a group of port classifiers in a list instvar $ptnotif_

NS2 Codes

I will conclude this post by showing how NS2 automatically propagates routing and agent-attaching commands.

1. Instproc add-route define in [f_NT]

I. [f_NT] Node::add-route { dst target }
-> rtnotif_ add-route $dst $target: This statement invokes instprocs add-route of the head routing module $rtnotif_. It tells the routing module that the packet whose destination is $dst should be forwarded to NsObject $target

II. [f_RT] RtModule instproc add-route { dst target }
-> [ $self set classifier_ ] install $dst $target: Install the NsObject $target into the slot number $dst of the instvar $classifier_
-> if { $next_rtm_ != "" } {
        $next_rtm_ add-route $dst $target
     }
     From the above figure, $next_rtm_ is the pointer to the next routing module in the address classifier group. This statement repeatedly invokes the add-route instproc from one to the next related routing module, until reaching the end of the chain.
     Again, the add-route command is entered through the head routing module, $rtnotif_. The command is then automatically propagate throughout all related routing module.

2. Instproc Node add-target defined in [f_NT]

I. [f_NT] Node::add-target { agent port }
-> foreach m [ $self set ptnotif_ ] {: $ptnotif_ is a list (i.e., array) variable. Each of its component is a routing module associated with a port classifier (see the above figure). So the following would be done to all routing modules within the port classifier group.
-> $m attach $agent $port: Install $agent in the slot number "$port" of the associated port classifier.
==============================================================

For more information about NS2, see Chapter 6 in the following book from Springer:
T. Issaraiyakul and E. Hossain, “Introduction to Network Simulator NS2”, Springer 2009.

You may also find lecture notes and other resource at the following website: http://www.ece.ubc.ca/~teerawat/NS2.htm

The Leader’s Purpose -- The Leader's Way, Chapter 4

2010-05-07T01:27:00.004-06:00

A leader needs to have wisdom (right view) and faith (support from followers). He must establish clear purposes for the company, and set the value that should be observed by all. He should act as an example to convince his follows to follow the principles.

Leaders' Roles
The leader's responsibilities include

Set the values and purposes of the organization,
Create faith, attract competent people, and encourage them to put great effort into the organization,
Provide communication systems for people inside the organization, and
Plan, organize, set priority, and make decisions.

A good leader should have technical knowledge and skill, determination, endeavor, and courage. The leader should understand the problem and know the solution. He or she should understand the organization and its people, culture and characteristics.

Organization Purposes
An organization should have purposes or mission statement. Main characteristics of good mission statements include

Clear and understandable,
Appeal to people in the organization,
Help people in the organization make decisions, and
Meaningful in different culture (in case of global organizations).

Google's mission statement: "To organize the world information and make it universally accessible and useful."

The eight worldly concerns

Leaders tend to see ups and downs very frequently. So, they should learn to be calm and collected when facing problems. When facing a problem, four pairs of worldly concerns usually arises. These concerns should be avoided, as they induce negative energy. Rather than focusing on these concerns, leaders should develop their mind by asking the following questions:

Being distressed when belittled and elated when praised -> What is the purpose of the person who belittles or praised me?
Being depressed and happy when facing failure and success, respectively -> What can I learn from the failure/success?
Being Disspirited and joyful when being poor and wealthy, respectively -> What can I do to better our status?
Being upset under the lack of recognition and pleased when being famous -> Am I getting arrogant?

Dealing with problems
Hard problems are difficult to deal with. It is better to break the problems down into the following questions:

What is the problem?
What is the cause of the problem?
What can I do to solve the problem?
How do I arrive the goals?

Source: THE Leader's Way: Business, Buddhism and happiness in an interconnected world by His Holyiness The Dalai Lama and Laurens Van Den Muyzenberg, Chapter 4 [Read the Book Review] [Read the Next Part].
---------------------------------------------------------------------------------------------------------
Book or Audiobooks?

[ns2] Do you really need NAM?

2010-05-05T04:39:00.001-06:00

NAM
Recently, I've got few people asking about installation NAM (network animator) in NS2. Usually it is quite straightforward to do it in Linux. But it's quite tricky in Windows (with Cygwin). To be honest, I have not tried to use NAM in Cygwin. If I have time, I might try and let you know.

Have Not Try?
You might wonder what I mean by I have not tried to use NAM. Won't I need it to do the research work? But the fact is I don't have any need to use NAM in my 10 years of research work.
Performance measures that I use are for example average and variance of throughput, delay, fairness, etc. These parameters cannot measured by NAM. That's why I have never use NAM. Because of this, I have never had problem of installing X-Window in Cygwin.

If not NAM, then What?
There are several other ways to measure performance. For example, if you would like to know TCP throughput, just print out the final sequence number of a TCP flow and divide that number by the simulation time.
In other cases, I do need to write the information to text files or analyze the trace file. I will blog about it. Please stick around.

Comments?
I will be interested to know the cases where NAM is required, apart from the fact that it nicely moves. If you have any, I would be appreciated if you let me know.

==============================================================

For more information about NS2, see the following book from Springer:
T. Issaraiyakul and E. Hossain, “Introduction to Network Simulator NS2”, Springer 2009.

You may also find lecture notes and other resource at the following website: http://www.ece.ubc.ca/~teerawat/NS2.htm

Doing the Right Thing -- The Leader's Way, Chapter 2

2010-05-01T07:53:00.004-06:00

"A leader will only be respected, when he acts according to the principles in which he said he believes."

Leaders and Their Roles

If the leader does not follow the principles, his followers will not follow the principles, but will follow the leaders’ whimsical will.

The roles of leaders include making decision and taking actions for the organization and people working for them. Leader should practice right conduct, which is achieved when acting according to right view.

"If the leader listens to you, it makes you feel valued and important."

Right conduct is an offspring of two following concepts: Right intention and wholesome actions.

Right Intention

Right intention refers to the care of well-being of the majority of people, not of everyone. This is because a benefit for a group of people can harm the others. It is quite impossible to make a decision which benefit everyone.

Wholesome decision

The decisions and actions must be wholesome. Wholesome refers to the following 6 perfections:

Generosity: Do not take all the credits. Give some to others.
Ethical discipline: Reach your goal ethically.
Patience: Suppress your negative emotion.
Enthusiastic effort: Be diligent.
Concentration: Focus. Do not let your attention shift while working on a certain thing.
Wisdom

"Worry is a waste of energy. It does not solve anything."

Apart from the above 6 perfections, the followings are considered wholesome as well

Humility: Be humble, listen, and admit mistakes.
Self-confidence
Consideration: Concern about well-being of others.
Equanimity: Be calm. Do not attach to bias or craving.
Having sense of shame.
Vigor
Receptivity and openminded.
Kindness

"Nothing can be gained by being unfriendly."

Source: THE Leader's Way: Business, Buddhism and happiness in an interconnected world by His Holyiness The Dalai Lama and Laurens Van Den Muyzenberg, Chapter 2 [Read the Book Review] [Read the Next Part].
---------------------------------------------------------------------------------------------------------
Book or Audiobooks?

Training the Mind -- The Leader's Way, Chapter 3

2010-04-23T23:54:00.004-06:00

Why do we want to train our mind?

The purpose of training your mind is to

Be clam, collected, and concentrated all the time (especially when making decision).
Enable the mind to analyze things quickly.

Training your mind to the perfection is too difficult. So you should aim at steady progress.

FAQ for Mind Training

Q: How can you find time to meditate?
A: You don’t need a lot of time. You can use the time that you have to wait for something. Five minutes would be quite sufficient.

Q: Do you need a spiritual teacher?
A: Yes, but you should assess the ability of the teacher first. The teacher should use his experience, not just follow the book. Once you have chosen a teacher, you should abide by his teaching. It is important to learn with doubt. Take his knowledge, not his words.

Simple techniques to train mind

The four main meditation approaches are walking meditation, sitting meditation, one-pointed meditation, and analytical mediation

Walking meditation

This is the simplest approach. The purpose is to develop the mindfulness and concentration, and the ability to observe when the emotion becomes active in the brain.

Walking meditation proceed as follows. As you walk, focus your body: Your legs, your feet, your steps, etc. Do not think of the pass nor the future. Focus at the present. Be mindful all the time. When your mind shift, bring it back.

Sitting meditation

Your activity affects your breathing. You hold your breath when you lift a heavy thing. You breathe quickly when you are excited. You can use your breathing to control your emotion and your mind.

When doing sitting meditation, sit with your back straight. Do not lean on anything, or you will be sleepy. Focus on your breathing only. When you breath in to fill up your stomach. Breath out to deflate your stomach. Each breathing should take 4-6 seconds. If you attention shifts, bring it back to your breathing.

One pointed meditation

Similar to the first two meditation. But this time focus your mind on an object such as a picture of forest. Focus on the picture only. Again, if your attention shift, bring it back.

Analytical meditation

Focus on a certain subject. Think and reason with one subject only. This type of meditation helps gain deeper insight into the subject you are focusing on.

Source: THE Leader's Way: Business, Buddhism and happiness in an interconnected world by His Holyiness The Dalai Lama and Laurens Van Den Muyzenberg, Chapter 3 [Read the Book Review] [Read the Next Part].
---------------------------------------------------------------------------------------------------------
Book or Audiobooks?

Commonly Used Windows Shortcuts

2010-04-21T04:29:00.002-06:00

Are you using Windows 7? Do you perfer keyboards to mouse? If you do, you might want to read on.

I am a Windows user, and I hate to take my hands off the keyboards. I love shortcuts. I am quite happy that Zia Munshi compiled and published 20 commonly used short-cut on Windows website. In fact, I learned it from Windows Weekly Show with Leo Laporte and Paul Thurrott. Feel free to check their websites out.

Commonly Used Windows Shortcuts

Basic shortcuts Ctrl+C, Ctrl+V, Ctrl+X, Ctrl+Z, Ctrl+A, Ctrl+P, Alt+Tab
Windows+D: Show desktops
Windows+Up arrow: Maximize windows
Windows+Down arrow: Minimize windows
Windows+Left/Right arrow: Snap windows to different position to on you screen. This short cuts work on multiple screen setting.
Windows+P: Switch among various multi-monitor setting.
Ctrl+Shift+Escape: Show task manage
Ctrl+L: Lock your computer
Ctrl+Click on taskbar: Switch between multiple instance under the same application. To try this, launch several IE instance. Then, click the taskbar icon while holding down the control key.
Shift+Click on taskbar: Launch an instance (e.g., a new windows of IE) .
Windows + '+'/Windows + '-': Zoom in and Zoom out

Assistance and Ethics

2010-04-20T10:15:00.000-06:00

How much help is too much?

Recently, I've received and seen quite a bit of emails asking for help. I understand the frustration. I was there, frustrated of not knowing what to do. But some of the questions went a bit overboard.
While I am willing to help, you've gotta help yourself too. Here are the questions that I don't think I will be able to comment on

I want to implement this protocol. Please send me the code.
I don't know what's wrong with the code. Can you help debugging my codes?

If the help you needed is one of the above, I might not be your best resource.

Ethics: Learning, not Delegating

I believe most people visiting this website would be students. What you need to keep in mind is the purpose of being who you are. The purpose of being a student is to learn, not to ask someone to do the homework for you. It is you who are learning, not me nor somebody else. So, it is you who will have to do the dirty work, and, in the process, learn something useful. I am here to help, not to do the work for you.
Note: While getting open-source code is ethical, it is your job to find the code and understand it. You might have to read the documentation, contact the authors, and/or go through the code. In the end, you will learn something, and you will be able to modified to code to fit your need.

Everything is important

A lot of students does not think highly of programming. They believe that their main objective is to learn telecommunications subjects, not programming. They are right. There are other methods to do high level study on telecommunications (e.g., mathematics). They don't need NS2. If you are one of them, do not spend too much time in NS2. You might be able to do high-level research without using NS2.

For me, I like NS2 because of its potential to do a lot of things. And, it help me and others understand telecommunications better. I believe that programming is as important as the subject I am interested in. So I painfully trained myself in programming and debugging. In the end, I am quite happy with things I learned and skills I obtained.
I believe everything is important. So I would like to share this mindset with you guys.

Services I Offer

After a long lecture about ethics and boring stuff, you might wonder "what do I get by visiting this website?'' I believe what this website offers is of interest to the general public (e.g., NS2 installation, including new modules into NS2, routing modules, etc.) If you have specific problem that I can help without breaking the above ethics, I will gladly help. Just post your question on my facebook fanpage.

Be Specific

Questions like "I want to implement a WFQ algorithm. How do I do that in NS2?'' are too broad, and would not comply with the above ethics. Again, this is you work, not mine. You have to work on that yourself so that you can learn something. Do the work until you run into a real problem like "I have implemented WFQ in C++. How do I integrated into Tcl?" Show me that you have done some work. And, I will point you to the right direction. You will feel more satisfied when you discover things by yourself, rather than having someone to tell you exactly what to do.

Synaptics: Disabling touch page, gestures, and more

2010-04-12T21:27:00.000-06:00

Are you using a laptop? Does your laptop has a TouchPad? Does the TouchPad messup with your typing rhythm? If so, read on.

Accidental Touch on a TouchPad: What's an annoyance

I've got a new Fujitsu S6420 few months ago. This is a nice laptop. The size is compact. It is easy to carry around. But because of its compactness, the touch pad is so close to keyboard. While typing my thumb would accidentally touch the touch pad. The cursor position would change and mess up my typing. I am kindda guy who don't like taking my hand off the keyboard. So, I get really annoyed when my hand accidentally touch the keypad.

Plugging Mouse Doesn't Help

Mouse isn't like headphone. In most computers, the speakers is disabled, when you plug in a headphone. Unfortunately, when you plug in a USB mouse. Both TouchPad and USB mouses work at the same time. So, plugging in a USB mouse doesn't help me.

My Savior: Synaptics

Google is my friend. I find this solution by googling "disabling TouchPad", and following webboards. I found the company Synaptic, which offers drivers for TouchPad [ here ]. It works! Here is how

What you need to do are

Download and install the driver [ Again from here ].
Restart your computer. Synaptics driver will appear on your taskbar (Arrows 1 and 2).
Open "Pointing Device Properties" (Arrow 3).
Click "Disable" (Arrow 4).

Done! Now, the only active device is your USB mouse. At anytime you can click enable to activate the TouchPad.

Additional Features

There are few more cool features with Synaptics. You can set them up by clicking "Settings..." (Arrow 5). You can see the details [ here ]

The followings are few features that I like (and use)

Scrolling:

Vertical scrolling: This is similar to wheel-mouse where you can move an active page up and down. Just place your finger on the right edge and drag up and down. Alternatively, you don't have to drag at the edge, if you use two fingers. Try it!
Horizontal scrolling: Similar to up-down scrolling, horizontal scrolling allows you to move page left and right. I find this feature quite useful when I am reading a document or viewing picture with large width. This time place your finger on the bottom of the touch and drag left and right.
Adjusting scrolling area: Another great things about Synaptics is it allows you to adjust the scrolling areas on the left and the bottom of the TouchPad. Just choose Scrolling->One-Finger-Scrolling->Scrolling Region and adjust the green area in the picture.
Chiral scrolling: Most TouchPads are very small. How much can you do vertical and horizontal scrolling? Not much, eh? Synaptics makes a cleaver move for TouchPad. Suppose you are doing a vertical scroll. You would touch the top of the scrolling area and drag down. When there is no way to go, you can make a clock-wise spiral move as in the picture. The active will keep scrolling down as long as you move your finger spirally. To scroll up, just reverse the spiral direction. Not surprisingly, this gesture works for horizon (left-right) scrolling as well.

Pinch Zoom

This feature works like multi-touch in iPhone. Just touch two points on a TouchPad. You can zoom in and out by dragging those two points closer and away, respectively, from each other

Edge Motion

Again, most touch pad is very small. One swipe might not bring a mouse pointer to the point you want. This is especially true for multi-monitor environment. With this feature, you can drag a pointer to the edge of the TouchPad in a single swipe. As long as your finger still touch the TouchPad, the mouse pointer will continue moving to the dragging direction. Again, you can also define the region where you call "edge" (like in scrolling).

There are more...

I just select few features that I like. There are a lot more features from Synaptics. Their utilities is not limited to TouchPad. Other utilities are for example ClickPad in MacBook.

Well, the best thing is that it works on almost any laptop and it's free!

Classifiers: A Multi-Target Packet Forwarder

2010-04-11T07:11:00.001-06:00

Note: This is a detailed note for the book, Introduction to Network Simulator NS2. You may have to read chapter 6 of the book for better understanding.

Introduction
This post is a sequel of the previous post, which demonstrated the relationship of classifiers, routing modules, and nodes:

What’s in This Post
I feel that before we can proceed further we need an understanding of what classifier is. Basically, it is an object which connects one NsObjects to several NsObjects. Note, in NS2 terminology, every object which can send and receive packets is called an NsObject.
I made up a presentation file which explains the concept of classifiers: What it is What's its purpose, How it works, How to configure it. Enjoy...

NS2 Classifiers

View more presentations from Teerawat Issariyakul.
========================================================
For more information about classifiers and routing module, see Chapter 6 in the following book from Springer:
T. Issaraiyakul and E. Hossain, “Introduction to Network Simulator NS2”, Springer 2009.

You may also find lecture notes and other resource at the following website: http://www.ece.ubc.ca/~teerawat/NS2.htm