[Help-gsl] how to seed qrng generators?

[Kevin Thornton]

Hi--

I'm trying to use the quasi-random sequence
generators, and I've been unable to figure out how to
seed them.  I've tried using the GSL_RNG_SEED
environment variable, which has had no effect.  I'm
working with the following example code for the
moment, and any advice would be appreciated:

#include<stdlib.h>
#include<stdio.h>
#include <gsl/gsl_qrng.h>
#include <gsl/gsl_rng.h>

int main(int argc, char **argv)
{  
  gsl_qrng * q;
  double priors[2];
  int i;
  gsl_rng * r;
  const gsl_rng_type * T;

  gsl_rng_env_setup();
  T = gsl_rng_default;
  r = gsl_rng_alloc (T);

  printf ("generator type: %s\n", gsl_rng_name (r));
  printf ("seed = %lu\n", gsl_rng_default_seed);
  printf ("first value = %lu\n", gsl_rng_get (r));
  q = gsl_qrng_alloc (gsl_qrng_sobol, 2);

  /* try setting to some initial value? */
  priors[0] = gsl_rng_uniform(r);
  priors[1] = gsl_rng_uniform(r);
  fprintf(stdout,"%f %f\n",priors[0],priors[1]);
  for(i=0;i<10;++i)
    {
      gsl_qrng_get(q,priors);
      fprintf(stdout,"%f %f\n",priors[0],priors[1]);
    }
}

Thanks,

Kevin

Kevin Thornton
Committee on Genetics
University of Chicago
http://www.molpopgen.org


                
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