/*
* Contributed by David Bauer, copied from chisq_poisson, with trivial
* modifications to change it to use the geometric distribution.
*/
double chisq_geometric(unsigned int *observed,double prob,int kmax,unsigned int nsamp)
{
unsigned int k;
double *expected;
double delchisq,chisq,pvalue;
/*
* Allocate a vector for the expected value of the bin frequencies up
* to kmax-1.
*/
expected = (double *)malloc(kmax*sizeof(double));
for(k = 0;k<kmax;k++){
expected[k] = nsamp*gsl_ran_geometric_pdf(k+1,prob);
}
/*
* Compute Pearson's chisq for this vector of the data with poisson
* expected values.
*/
chisq = 0.0;
for(k = 0;k < kmax;k++){
delchisq = ((double) observed[k] - expected[k])*
((double) observed[k] - expected[k])/expected[k];
chisq += delchisq;
if(verbose == D_CHISQ || verbose == D_ALL){
printf("%u: observed = %f, expected = %f, delchisq = %f, chisq = %f\n",
k,(double)observed[k],expected[k],delchisq,chisq);
}
}
if(verbose == D_CHISQ || verbose == D_ALL){
printf("Evaluated chisq = %f for %u k values\n",chisq,kmax);
}
/*
* Now evaluate the corresponding pvalue. The only real question
* is what is the correct number of degrees of freedom. We have
* kmax bins, so it should be kmax-1.
*/
pvalue = gsl_sf_gamma_inc_Q((double)(kmax-1)/2.0,chisq/2.0);
if(verbose == D_CHISQ || verbose == D_ALL){
printf("pvalue = %f in chisq_geometric.\n",pvalue);
}
free(expected);
return(pvalue);
}
double
test_geometric1_pdf (unsigned int n)
{
return gsl_ran_geometric_pdf (n, 1.0);
}
