From help-octave-request at bevo dot che dot wisc dot edu  Wed Jun 20 23:57:39 2001
Subject: Re: How to speed up Octave
From: Jonathan Drews <j dot e dot drews at worldnet dot att dot net>
To: laubach at neuro dot duke dot edu (Laubach, Mark (Nicolelis Lab))
Cc: help-octave at bevo dot che dot wisc dot edu
Date: Wed, 20 Jun 2001 23:56:11 -0500

Hi Mr. Laubach:

On Tuesday 19 June 2001 12:27, Laubach, Mark (Nicolelis Lab wrote:

>  Can someone please suggest how I might improve execution speeds for
> Octave, especially under Linux?


 My execution speeds for the above commands were comparable to yours. There 
doesn't appear any simple way to boost Octaves computational speed. I found 
that Scilab did one of the computations in 76 seconds:

timer();B=inv(A)*A;timer()
 ans  =
 
    76.19  

 The easiest way to boost the performance of your Octave calculations is to 
do all the calculations at once and minimize the Octave windows while you go 
about other tasks like getting e-mail and writing reports or drawing up stuff 
in Xfig. The point is: exploit the multitasking capacity of Linux and the 
fact that Octave is open source to obtain maximum productivity. Octave, being 
open source, has no site license. Unlike Matlab, you can run as many of them 
as you wish. I ran 3 Octaves and one Scilab at the same time while having 
Star Office open and getting e-mail. 

Running all there at once gave:
octave:3> tic;A=rand(20,20000);B=svd(A);toc
ans = 2.9185
octave:3> tic;A=rand(2000,2000);B=prod(A);toc
ans = 10.034
octave:4> tic;A=rand(1000,1000);B=A\A;toc
ans = 52.421

So the time to completion was 52.4 sec; the limiting calculation.  I am using 
a 600 MHz P III. I also think Dimitri makes a good point; the rand() has 
varying computation times. So the true measure is:

octave:4> tic;A=rand(20,20000);toc
ans = 0.85655
octave:5> tic;B=svd(A);toc
ans = 1.6908

octave:4> tic;A=rand(2000,2000);toc
ans = 4.4912
octave:5> tic;B=prod(A);toc
ans = 0.35511

octave:5> tic;A=rand(1000,1000);toc
ans = 1.1226
octave:6> tic;B=A\A;toc
ans = 44.998

All run concurrently.
-- 
						Cheers,


						Jonathan



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