bugGNU Scientific Library - Bugs: bug #28267, poor convergence region for...


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bug #28267: poor convergence region for gsl_sf_hyperg_1F1

Submitter:  -Deleted Account- <bjg>
Submitted:  Fri 11 Dec 2009 08:35:17 PM UTC
Category:  Accuracy problem Severity:  3 - Normal
Operating System:  Status:  Postponed
Assigned to:  None Open/Closed:  Open
Release:  1.13

Thu 25 Feb 2010 03:42:25 PM UTC, comment #2: 

I cannot find any algorithm which handles this case.

-Deleted Account- <bjg>
Fri 11 Dec 2009 08:36:23 PM UTC, comment #1: 

It's inherently difficult to compute the value in this region either way as there is massive cancellation in both the series and the Kummer transformed series.

-Deleted Account- <bjg>
Fri 11 Dec 2009 08:35:17 PM UTC, original submission:  

The magnitude of the error is greater than the value itself for
a<<0, b>0, x>>0

gsl_sf_hyperg1F1(-3.78e+01, 2, 1.035e+02) =>  -7.00055e+18 +/- 3.77654e+19

From: Weibin Li <weibinli@mpipks-dresden.mpg.de>
To: -email is unavailable-
Subject: [Bug-gsl] gsl_sf_hyperg_1F1
Date: Mon, 30 Nov 2009 15:26:11 +0100

Hi, guys

I experienced bugs with gsl_sf_hyperg_1F1. The version  is gsl_1.12, but
the testing is also done with gsl_1.13, using a  mac with version 10.5.8
and hp-workstation with gnome_2.24.1.

#include "gsl/gsl_sf_hyperg.h"

int main(int argc, char **argv)
 int ii;
 double Ri;
 double v0;
 gsl_sf_result r;
 for(ii = 10; ii< 140;ii++)
     Ri = 2013;
     v0 =38.86871 +ii*2.5e-10;


return 0;

The output of above code shows an extremely large error. by increasing
Ri, the relative error decreases. Is there any idea to fix this?

Thank you very much.



-Deleted Account- <bjg>


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Attached Files
file #19240:  hyperg1F1.c added by bjg (429B - text/x-csrc)


Depends on the following items: None found

Items that depend on this one: None found


CC list is empty


Follow 2 latest changes.

Date Changed by Updated Field Previous Value => Replaced by
2010-02-25 bjg StatusConfirmed Postponed
2009-12-11 bjg Attached File- Added hyperg1F1.c, #19240

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