Re: [Bug-gsl] Bug in gsl_sf_hyperg_2F1 ??

[Ralph Silva]

Hi

I don't know much about this function. But I think it must be a restriction
with the range of a, b and c in your code. If you try  a = 9.9999999999; for
instance, it will work. I don't know what the behavior we should expect.

You can also check the source file /gsl-1.11/specfunc/hyperg_2F1.c I've got
an error message pointing to line 750 in this source file when I ran your
program.

I hope that gives you some idea.
Ralph.

On Sat, Nov 8, 2008 at 1:00 PM, Didier Pinchon <address@hidden>wrote:

> Hello,
>
> I have tried to compute 2F1(11, -1 ; 11/2; 0.125) and I got an error
> message (below is my sample program).
> However 2F1(-1, 11 ; 11/2; 0.125) provides the right result 0.75
>
> Am I wrong somewhere ?
> I did not find any indication in archives.
>
> Thank you for your help.
> All the best,
> Didier
>
> -----------------------------------------------------------------------------
> /* bug_gsl.c */
> /* 2F1(11,-1 ; 11/2 ; 1/8) = 0.75 */
> /* Didier Pinchon, 8 Nov 2008 */
> #include <stdio.h>
> #include <stdlib.h>
> #include "gsl_math.h"
> #include "gsl_sf_hyperg.h"
>
> int main()
> {
>  double a,b,c,r, res;
>  a = 10.0;
>  b = -1.0;
>  c = 5.5;
>  r = 0.125;
>
>  res = gsl_sf_hyperg_2F1(a,b,c,r);
>
>  printf("res = %20.14e\n", res);
>  return EXIT_SUCCESS;
> }
>
> /* Compilation and execution:
> $ gcc -o bug_gsl -I/usr/local/include/gsl bug_gsl.c -L/usr/local/lib -lgsl
> -lm
>
> $ ./bug_gsl
> gsl: hyperg_2F1.c:750: ERROR: error
> Default GSL error handler invoked.
> Abandon
>
> */
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