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Speed Optimization on Fix Matrix Looping
From: |
lain.ux |
Subject: |
Speed Optimization on Fix Matrix Looping |
Date: |
Sun, 04 May 2008 18:31:38 +0000 |
User-agent: |
Icedove 1.5.0.14pre (X11/20080305) |
Hi,
I have tried to run my octave code with following two test cases and
gotten the elapsed time. As the result, test case 2 is executed much
faster than case 1.
Case 1:
b = [];
for i = 1:N
b(i, 1:P) = i * ones (1, P);
endfor
Case 2:
b = 1.0 * ones (N, P); # this line doesn't effect the final matrix b
# value. but with this line, the execution time
# becomes much-much faster
for i = 1:N
b(i, 1:P) = i * ones (1, P);
endfor
My platform:
- Processor: Intel Core 2 Duo
- Operating System: Debian GNU/Linux 4
- Octave Version: 3.0.1
My questions are:
1) Is the test result correct?
2) Has anyone test about it?
Suggestion:
I see that b = []; is mostly used on Octave codes. If the result is
correct (can improve the speed), I think, it better to be changed
automatically during the parsing step so needless for user to change the
line manually.
Please find the complete test code and result from my blog:
http://l411v.blogspot.com/2008/04/octave-speed-optimization-080426.html
Thanks,
lain.ux
- Speed Optimization on Fix Matrix Looping,
lain.ux <=