Error in evaluating Poisson CDF

[Sebastiano Vigna]

This program

#include <gsl/gsl_cdf.h>
#include <stdio.h>
int main() {
        printf("%f\n", gsl_cdf_poisson_Q(7165697, 7168929.393553));
}

prints

gsl: gamma_inc.c:181: ERROR: error in large x asymptotic
Default GSL error handler invoked.
Aborted (core dumped)

on gsl 2.6 (Fedora Linux). scipy, for instance, has no problem in evaluating it:

>>> scipy.stats.poisson.sf(7165697, 7168929.393553);
0.8863015162515768

This kind of error is reported a bit randomly with certain large parameters 
(I'm running a large number of collision tests for PRNGs, and the distribution 
of collisions is approximated by a Poisson distribution, so I'm evaluating a 
lot of those with different parameters). I can provide more examples if this is 
useful in understanding the problem.

Ciao,

                                        seba