[Help-gsl] Failure in gsl_cdf_fdist_Pinv

[Wang, Gao]

Dear All,

I am (fortunately) running into a problem with gsl_cdf_fdist_Pinv. It is
not happy to work with some numbers, giving an error message:

gsl: betainv.c:181: ERROR: inverse failed to converge
Default GSL error handler invoked.
Aborted

Below is the test codes, where the firlst 5 lines are fine, but the last
two lines are problematic.

===============================================
// test is on gsl-1.15. To compile the code:
// g++ test.cpp -lgsl -lgslcblas -lm

#include "gsl/gsl_randist.h"
#include "gsl/gsl_cdf.h"
#include <iostream>
using namespace std;

int main()
{
  //cout << gsl_cdf_fdist_Pinv(0.975, 50, 100) << endl; // OK
  //cout << gsl_cdf_fdist_Pinv(0.975, 10, 20000) << endl; // OK
  //cout << gsl_cdf_fdist_Pinv(0.975, 11, 19999) << endl; // OK
  //cout << gsl_cdf_fdist_Pinv(0.975, 10, 20000000) << endl; // OK
  //cout << gsl_cdf_fdist_Pinv(0.975, 13, 19993) << endl; // OK
  cout << gsl_cdf_fdist_Pinv(0.975, 11, 19999000) << endl; // ERROR
  cout << gsl_cdf_fdist_Pinv(0.975, 16, 19993) << endl; // ERROR
  return 0;
}
===============================================

Looking forward to hearing from you on this issue!

Kindest regards,
Gao
Student in Statistical Genetics, Baylor College of Medicine