Hello,
I noticed the following behaviour when initialising the random number
generator on a 64bit machine. Basically, on a 64 bit machine, the
unsigned long int probably provokes an overflow in the gsl_rng_set()
function, so that the initialisation of the seed in some way fails, and
I got always identical numbers despite different seeds. Here is part of
the code that made the overflow:
unsigned long int un_seed = GetSomeSeed(); // this function returns a
random number in [0,ULONG_MAX]
gsl_rng_env_setup();
T = gsl_rng_default;
gsl_rng* r = gsl_rng_alloc ( T );
gsl_rng_set ( r, un_seed ); // here probably the overflow
int value = gsl_rng_uniform_int(r, 1000); // retruns always the same
number, despite different seeds
For the time being, I bypassed the problem by limiting the seed to
UINT_MAX, which does not produces overflows on the 64bit machines.
I hope this report is useful....
regards,
Vito
--
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Vito Trianni, Ph.D. vito.trianni@(no_spam)istc.cnr.it
CNR-ISTC
http://iridia.ulb.ac.be/~vtrianni
via San Martino della Battaglia, 44
00185 Roma Tel: +39 06 44595 215
Italy Fax: +39 06 44595 243
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