Gui Guan's BLOG

Quartz-like Crystals Found in Planetary Quartz-like crystals found in planetary disks

Gui Guan — Thu, 20 Nov 2008 02:36:18 +0000

NASA's Spitzer Space Telescope has, for the first time, detected tiny quartz-like crystals sprinkled in young planetary systems. The crystals, which are types of silica minerals called cristobalite and tridymite, can be seen close-up in the black-and-white insets (cristobalite is on the left, and tridymite on the right). The main picture is an artist's concept of a young star and its swirling disk of planet-forming materials.Courtesy NASA/JPL-Caltech

A small but very hard to find bug

Gui Guan — Sat, 27 Sep 2008 14:31:55 +0000

Bug is a very disgusting thing in Computer Science. In one of my subjects project, I was required to write a Hearts card game robot player. I spent several hours finished the code, but it took me 2 days to debug it. :-(. A tiny bug found in the debugging process took me a whole night, which resulted to be mistyping variable Card as C, very embarrassed!

The funniest thing was that in order to find that tiny bug, I used a screen recording software recorded the whole playing process, then simulated the whole process by re-watching the recorded video again and again, but finally came to the conclusion that there was no bug in my program! I was nearly desperate, fortunately, an accidental warning msg “singleton variable” saved my life.

Here is the video I recorded:

after playing for awhile, my robot(bottom one) stopped play.

Will cities of the future look like Beijing, pictured here?

Gui Guan — Thu, 12 Jun 2008 12:16:12 +0000

Cities are an important testing ground for green technologies because urbanization is accelerating rapidly. More than half of the world’s population now lives in cities–and most population growth in coming decades will happen there, mostly in developing countries.

Will cities of the future look like Beijing, pictured here?

read all texts about Cities go green

eclipse CDT + mingw + gtk + cairo under Windows XP

Gui Guan — Fri, 06 Jun 2008 16:25:14 +0000

Finally, I managed to compile a gtk + cairo GUI program by using mingw GNU make and eclipse CDT under Windows XP.

Map: What Does the Internet Look Like?

Gui Guan — Sun, 02 Mar 2008 12:52:11 +0000

Emacs入门指南

Gui Guan — Wed, 13 Feb 2008 13:39:25 +0000

Emacs入门指南(1)

Emacs入门指南(2)

Emacs入门指南(3)

LDBL_MAX -1.#QNAN0e+000 with MinGW?

Gui Guan — Thu, 22 Nov 2007 05:14:19 +0000

I have tried to run this with both eclipse(CDT)+MinGW and Cygwin+GCC

#include 
#include 
#include 
 
int main()
  {
    puts("The range of ");
    printf("\tlong double is [%Le, %Le]∪[%Le, %Le]\n", -LDBL_MAX, -LDBL_MIN, LDBL_MIN, LDBL_MAX);
    return EXIT_SUCCESS;
  }

but got different results:

In eclipse(CDT)+MinGW
The range of
long double is [-1.#QNAN0e+000, 3.237810e-319]∪[6.953674e-310, 0.000000e+000]
In Cygwin+GCC
The range of
long double is [-1.189731e+4932, -3.362103e-4932]∪[3.362103e-4932, 1.189731e+4932]

This is weird, and I googled it, then just found this http://www.thescripts.com/forum/thread498535.html

The LDBL_MAX of long double is machine-dependent, but why it like this in same machine? I guess it’s the problem with MinGW. Anyone hv any idea?

Append Session ID(SID) to Url Automatically When Cookies Are Forbidden

Gui Guan — Wed, 14 Nov 2007 07:36:19 +0000

Today, when I was reviewing the session part of PHP, I suddenly came out a question: how to make PHP to append session ID(SID) to your page links automatically when cookies are forbidden in that browser? I managed to do this in JSP, but not sure whether the PHP can also handle this problem.

I checked the configuration files (php.ini) for my apache server, and there is a session section, under which there is a setting session.use_trans_sid = 0. After I changed this to session.use_trans_sid = 1, and restarted apache, the links of the page which invoked session_start() have now appended the SID. There is also an url_rewriter.tags, with which you can define what elements of a page will be appended.

Here are some demo codes:

sessions.php

 ob_start(); ?>



	Untitled

 


	ini_set('session.use_trans_sid','1'); //you can also do this instead of modify php.ini
	session_start();
	$_SESSION['test']='right!';
	//header('Location: sessions2.php'); //SID won't be appended in this situation
	//exit();
?>
click here


 ob_end_flush(); ?>

sessions2.php

 ob_start(); ?>



	Untitled

 


	session_start();
	echo $_SESSION['test'];
?>
 


 ob_end_flush(); ?>

Make the Most of Taking Lecture Notes

Gui Guan — Sat, 13 Oct 2007 12:59:09 +0000

In many of your classes, your instructor lectures on or makes a presentation about a topic, usually one that’s related to the current subject you’re studying. During a class lecture, your job is to listen actively and to take notes to reinforce what you’ve heard and jog your memory about the key points being presented.

Instead of writing down every word, listen — really listen — and put the information in perspective. What’s truly important to understand and remember? What’s not? Look for alerts from the lecturer, who may indicate significant information by repeating it, giving multiple examples, writing on the board, gesticulating or speaking forcefully, or giving word clues (”Two important reasons . . .” “Opposing viewpoints from . . .” “The result underscored . . .”).

You may see another student furiously taking notes and think you should be too. Don’t worry about what’s on your neighbor’s mind; just listen carefully to the lecture and trust your judgment.

Make note-taking easier with these tips:

Include the date, instructor, and title of the lecture (if available). Add the textbook chapter, part, or pages on which the lecture is based.
If the lecture is based on a reading assignment, make sure you’ve done the reading and have taken notes on the reading. If you understand the material from the reading assignment, you’ll have a good idea of the structure of the lecture and the key points. This helps you decide what to note and what to let pass. If the instructor adds facts, concepts, or new ideas-or disagrees with the reading assignment-these are big clues that you should be paying attention and taking notes on these ideas.
If the instructor provides an overview of the lecture, structure your notes in an outline form so you can understand how the ideas relate. Indent lines, draw arrows, and use bullets to organize information. After class, review and revise your notes if the structure and organization of the lecture isn’t clear.
Paraphrase the lecturer’s words. Note key concepts or terms, even if you don’t know what they mean. Flag them to check the meanings later. If you aren’t sure of the spelling, make a note (such as, “sp?”) next to the term so that you can revisit the spelling and/or meaning.
You may not be able to get all the details, but seek to capture the main ideas, and then leave blanks to fill in the detail later. For example, if the instructor is talking about the five events leading up to the Civil War, it’s more important to write down the events than getting details of each one.
Record your questions (or questions you think the instructor may ask on a test based on the lecture content).

If you occasionally can’t understand your own notes, don’t despair. Note-taking gets better with practice.

CliffsNotes.com. Make the Most of Taking Lecture Notes. 13 Oct 2007
<http://www.cliffsnotes.com/WileyCDA/Section/id-305416,articleId-28803.html>.

Age 1.0beta1

Gui Guan — Wed, 10 Oct 2007 00:43:45 +0000

Here is my first Robocode robot - Age.

No need to have an introduction, just have a try if you want. BTW, it uses anti-gravity motion.

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