Gui Guan’s BLOG
There’s more than one way to do it
Quartz-like Crystals Found in Planetary Quartz-like crystals found in planetary disks
Author: Gui Guan20 Nov
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
Author: Gui Guan28 Sep
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?
Author: Gui Guan12 Jun
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?
eclipse CDT + mingw + gtk + cairo under Windows XP
Author: Gui Guan7 Jun
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?
Author: Gui Guan2 Mar
Emacs入门指南
Author: Gui Guan13 Feb
LDBL_MAX -1.#QNAN0e+000 with MinGW?
Author: Gui Guan22 Nov
I have tried to run this with both eclipse(CDT)+MinGW and Cygwin+GCC
1 2 3 4 5 6 7 8 9 10 | #include <stdio.h> #include <stdlib.h> #include <float.h> 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
Author: Gui Guan14 Nov
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
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 | <?php ob_start(); ?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html> <head> <title>Untitled</title> </head> <body> <?php 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(); ?> <a href="sessions2.php">click here</a> </body> </html> <?php ob_end_flush(); ?> |
sessions2.php
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 | <?php ob_start(); ?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html> <head> <title>Untitled</title> </head> <body> <?php session_start(); echo $_SESSION['test']; ?> </body> </html> <?php ob_end_flush(); ?> |
Make the Most of Taking Lecture Notes
Author: Gui Guan13 Oct
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 . . .”). Read the rest of this entry »
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