bug

[Fernando <fpilotto at conex dot com dot br>]

Hi,
I have found a bug in the hypergeometric function routine, F(a,b,x).
When a is negative ( a<-2), the function has a discontinuity.
I have include a program which just plots the function.
In the program is commented at which values of x the discontinuity
begins.

thank you,
Fernando Pilotto
/*  command used: */
/*  gcc plot_gsl_hyperg.c -lgsl -lgslcblas -lm; ./a.out > out */

#include "stdio.h"
#include "math.h"
#include "gsl/gsl_sf_hyperg.h"

main ()
{
  double r,f;

  for ( r=0.0; r<8.0; r += 0.01)
    {
/*    f = gsl_sf_hyperg_1F1(-4.5,1.0,r); */ /*  discontinuity around r=9 */
/*    f = gsl_sf_hyperg_1F1(-2.5,1.0,r); */ /*  discontinuity: r=5 to r=6 */
      f = gsl_sf_hyperg_1F1(-2.05,1.0,r); /*  discontinuity at r=5 */
      printf("%f   %f\n", r, f);
    }
  return 1;
}