[Bug-gsl] [bug #45730] Inaccurancy problems in the function bessel_j2

[Enyi Tang]

URL:
  <http://savannah.gnu.org/bugs/?45730>

                 Summary: Inaccurancy problems in the function bessel_j2
                 Project: GNU Scientific Library
            Submitted by: eytang
            Submitted on: Tue 11 Aug 2015 01:01:01 AM GMT
                Category: Accuracy problem
                Severity: 3 - Normal
        Operating System: 
                  Status: None
             Assigned to: None
             Open/Closed: Open
                 Release: GSL-1.16
         Discussion Lock: Any

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Details:

I find the result of gsl_sf_bessel_j2 at large input is wrong. But the results
of gsl_sf_bessel_j0 and gsl_sf_bessel_j1 are right. A test case is attached,
and I will further investigate the reason and may provide some clues from the
code. The outputs of the attached test case are as follows with the latest
version of GSL in git. The version hash is
867624b55b20de8da80d23d90549c74ec24cb3a6 on Aug. 7, 2015.


gsl_sf_bessel_j0(-1.000000e+22): -0.000000 
gsl_sf_bessel_j1(-1.000000e+22): 0.000000 
gsl_sf_bessel_j2(-1.000000e+22):
183552123001419854904449771500981977088.000000 
gsl_sf_bessel_j0(-1.000000e+21): -0.000000 
gsl_sf_bessel_j1(-1.000000e+21): 0.000000 
gsl_sf_bessel_j2(-1.000000e+21): -92157107960277832260219441795563520.000000 
gsl_sf_bessel_j0(-1.000000e+20): -0.000000 
gsl_sf_bessel_j1(-1.000000e+20): 0.000000 
gsl_sf_bessel_j2(-1.000000e+20): -9155440021830429048832.000000 
gsl_sf_bessel_j0(-1.000000e+19): -0.000000 
gsl_sf_bessel_j1(-1.000000e+19): -0.000000 
gsl_sf_bessel_j2(-1.000000e+19): 2.888382 
gsl_sf_bessel_j0(-1.000000e+18): -0.000000 
gsl_sf_bessel_j1(-1.000000e+18): 0.000000 
gsl_sf_bessel_j2(-1.000000e+18): 0.000000 
gsl_sf_bessel_j0(-1.000000e+17): -0.000000 
gsl_sf_bessel_j1(-1.000000e+17): -0.000000 
gsl_sf_bessel_j2(-1.000000e+17): 0.000000 
gsl_sf_bessel_j0(1.000000e+17): -0.000000 
gsl_sf_bessel_j1(1.000000e+17): 0.000000 
gsl_sf_bessel_j2(1.000000e+17): 0.000000 
gsl_sf_bessel_j0(1.000000e+18): -0.000000 
gsl_sf_bessel_j1(1.000000e+18): -0.000000 
gsl_sf_bessel_j2(1.000000e+18): 0.000000 
gsl_sf_bessel_j0(1.000000e+19): -0.000000 
gsl_sf_bessel_j1(1.000000e+19): 0.000000 
gsl_sf_bessel_j2(1.000000e+19): 2.888382 
gsl_sf_bessel_j0(1.000000e+20): -0.000000 
gsl_sf_bessel_j1(1.000000e+20): -0.000000 
gsl_sf_bessel_j2(1.000000e+20): -9155440021830429048832.000000 
gsl_sf_bessel_j0(1.000000e+21): -0.000000 
gsl_sf_bessel_j1(1.000000e+21): -0.000000 
gsl_sf_bessel_j2(1.000000e+21): -92157107960277832260219441795563520.000000 
gsl_sf_bessel_j0(1.000000e+22): -0.000000 
gsl_sf_bessel_j1(1.000000e+22): -0.000000 
gsl_sf_bessel_j2(1.000000e+22): 183552123001419854904449771500981977088.000000




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File Attachments:


-------------------------------------------------------
Date: Tue 11 Aug 2015 01:01:01 AM GMT  Name: gslbesseljtest.c  Size: 672B  
By: eytang

<http://savannah.gnu.org/bugs/download.php?file_id=34621>

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