[Bug-gsl] [bug #45926] error in generalized hypergeometric function

[Patrick Alken]

URL:
  <http://savannah.gnu.org/bugs/?45926>

                 Summary: error in generalized hypergeometric function
                 Project: GNU Scientific Library
            Submitted by: psa
            Submitted on: Fri 11 Sep 2015 10:09:01 AM GMT
                Category: Runtime error
                Severity: 3 - Normal
        Operating System: 
                  Status: None
             Assigned to: None
             Open/Closed: Open
                 Release: 
         Discussion Lock: Any

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Details:

from aim =at= stats =dot= uwo =dot= ca

The bug I am reporting arose when I tried to the gsl package in R:
gsl: wrapper for the Gnu Scientific Library

The authors of the gsl package have determined that the error is in the Gnu
Scientific Library.

The problem arises with the generalized hypergeometric function and is
illustrated
in the code below. Please excuse my odd syntax where I used 1+9 etc instead of
10
etc. Both Mathematica and MatLab get the result correct.

Browse[2]> hyperg_2F1(-0.2,-0.2 + 9,1 + 9,0.8)
[1] 0.7799897
Browse[2]> hyperg_2F1(-0.2,-0.2 + 10,1 + 10,0.8)
[1] NaN


MATHEMATICA GETS IT CORRECT
Hypergeometric2F1[-0.2, -0.2+9, 1+9, 0.8]
0.77999
Hypergeometric2F1[-0.2, -0.2+10, 1+10, 0.8]
0.775746

MATLAB GETS IT CORRECT
>> hypergeom([-0.2,-0.2+9],1+9,0.8)

ans =

    0.7800

>> hypergeom([-0.2,-0.2+10],1+10,0.8)

ans =

    0.7757






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