l i n u x - u s e r s - g r o u p - o f - d a v i s
L U G O D
 
Next Meeting:
August 5: Social gathering
Next Installfest:
TBD
Latest News:
Jul. 4: July, August and September: Security, Photography and Programming for Kids
Page last updated:
2002 Apr 02 14:47

The following is an archive of a post made to our 'vox-tech mailing list' by one of its subscribers.

Report this post as spam:

(Enter your email address)
Re: [vox-tech] random number in C
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [vox-tech] random number in C



On Tue, Apr 02, 2002 at 10:05:34AM -0800, Peter Jay Salzman wrote:
> i wrote some monte carlo code which obtains a random generator seed
> through a read to /dev/random.
> 
> on a lark, i did a run:
> 
> 	T: 4.0e+00  beta: 2.500e-01  trials: 1000000
> 	N: 10  M: 10  seed: 208006379

What code did you use to read from /dev/random(provide source)?  
What exact call did you call with rand() (provide source)?  
How exactly did you initialize the random number generator (provide source)?

You did pass the seed to srand() and not rand() right?

> the seed for these two runs is the same.  i would've expected that calls
> to rand() should've generated the same set of random numbers.  yet the
> different runs of the monte carlo code yield different results, which is
> fine, except i was expecting it to be exactly the same since the seed is
> the same.

A reasonable expectation.

If you port to any other platform you should use random and srandom
which provides for higher quality implemtnations on most platforms
(besides linux).   It also allows you to set a more complex seed.

-- 
Bill Broadley
Mathematics/Institute of Theoretical Dynamics
UC Davis
_______________________________________________
vox-tech mailing list
vox-tech@lists.lugod.org
http://lists.lugod.org/mailman/listinfo/vox-tech



LinkedIn
LUGOD Group on LinkedIn
Sign up for LUGOD event announcements
Your email address:
facebook
LUGOD Group on Facebook
'Like' LUGOD on Facebook:

Hosting provided by:
Sunset Systems
Sunset Systems offers preconfigured Linux systems, remote system administration and custom software development.

LUGOD: Linux Users' Group of Davis
PO Box 2082, Davis, CA 95617
Contact Us

LUGOD is a 501(c)7 non-profit organization
based in Davis, California
and serving the Sacramento area.
"Linux" is a trademark of Linus Torvalds.

Sponsored in part by:
EDGE Tech Corp.
For donating some give-aways for our meetings.