view xthresh.c @ 284:cacad987d785

Really finish with the sampling branch, this time merging all of it,
yes, even the last revision.  (The last revision was one that seeded the
RNG with the current time, which is helpful when trying to get multiple
independent-ish samples from the same database...)

#include <gsl/gsl_sf.h>
#include <stdio.h>
#include <stdlib.h>
#include <math.h>

int main(int argc, char *argv[]) {
  if(argc != 4) {
    fprintf(stderr, "Wrong number of arguments: %d\n", argc);
    exit(1);
  }

  long int meanN = strtol(argv[1], NULL, 10);

  double d = strtod(argv[2], NULL);
  double sigma2 = strtod(argv[3], NULL);

  double logw = (2 / d) * gsl_sf_log(-gsl_sf_log(0.99));
  double logxthresh = gsl_sf_log(sigma2) + logw
    - (2 / d) * gsl_sf_log(meanN)
    - gsl_sf_log(d/2)
    - (2 / d) * gsl_sf_log(2 / d)
    + (2 / d) * gsl_sf_lngamma(d / 2);

  printf("w: %f\n", exp(logw));
  printf("x_thresh: %f\n", exp(logxthresh));
  exit(0);
}