[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
generating random numbers  what seeds to use?
From: 
John W. Eaton 
Subject: 
generating random numbers  what seeds to use? 
Date: 
Sun, 27 Apr 2003 20:03:41 0500 
On 27Apr2003, Mike Miller <address@hidden> wrote:
 I need to create large amounts of random data under a certain model. I
 wanted to produce 10,000 files, so I set 10 different processors to the
 task of executing an octave scrit that would make 1,000 files.
 Unfortunately, I forgot that some of the jobs were starting at nearly the
 same moment, so they took the same seed from the clock and produced the
 same 'random' files!

 I'd still like to run 10 jobs at once, but I'll have to supply initial
 seeds. Is there any way that I can guarantee that I won't produce the
 same file twice? What is the best way to choose seeds? What is the
 period for Octave's random number generator? Has anyone developed other
 random number generators for Octave?
Why not generate all the random numbers in advance? For example, for
N random numbers in each of M files, something like
for i = 1:M
f = fopen (sprintf ("rnd%d", i), "w");
fwrite (f, rand (N, 1), "double");
fclose (f);
endfor
Then you could read these files for your data generation processes.
jwe

Octave is freely available under the terms of the GNU GPL.
Octave's home on the web: http://www.octave.org
How to fund new projects: http://www.octave.org/funding.html
Subscription information: http://www.octave.org/archive.html
