Using version 2.6 of GSL from ftp://ftp.gnu.org/gnu/gsl/gsl-2.6.tar.gz
OS is Ubuntu 18.04.2 LTS
Hardware is a Dell workstation with a 3.60 GHz Intel i7-4790 and 32 GB
of RAM
Compiler is gcc 7.4.0 with the -w option
When the first argument is infinity, gsl_sf_gamma_inc_P consistently
returns 0. Meanwhile, the implementations in SciPy, mpmath, and the JMAT
library all recognize this as an erroneous computation and throw exceptions
or return NaNs
#include <gsl/gsl_sf.h>
#include <stdio.h>
#include <gsl/gsl_math.h>
int main (void){
double out;
out = gsl_sf_gamma_inc_P(GSL_POSINF, 22);
printf("%f\n", out);
printf("%.21e\n", out);
return 0;
}
Best,
Jackson Vanover
