[Bug-gsl] [bug #52927] make check fails on Bessel j2 test

[Vladimir]

Follow-up Comment #2, bug #52927 (project gsl):

I do confirm this error. Our cluster uses CentOS 6 as well and gives _almost_
_exactly_ the same values:

$ uname -r
2.6.32-642.6.1.el6.x86_64
$ ldd --version
ldd (GNU libc) 2.12
$ gcc --version
gcc (GCC) 5.5.0



FAIL: gsl_sf_bessel_j2_e(1048576.0, &r) [168]
  expected: -3.1518539455252412e-07
  obtained: -3.1518539455252539e-07 +/- 2.7994086564622246e-22
(rel=8.88178e-16)
  fracdiff: 2.0155588470164931e-15
 tolerance: 4.5474735088646412e-13
  value/expected not consistent within reported error
  -3.151853945525253879e-07  2.799408656462224591e-22
FAIL: Bessel Functions [407]

Updating gsl to version 2.5 fixes this problem.

At the same time I have no problems with my desktop:

$ uname -r 
4.17.3-200.fc28.x86_64
$ ldd --version
ldd (GNU libc) 2.27
$ gcc --version
gcc (GCC) 8.1.1 20180712 (Red Hat 8.1.1-5)


I also would like to report a bug here since it's related to Bessel functions.
According to this
<https://stackoverflow.com/questions/36903384/c-gsl-bessel-function-example>
an example from the documentation gives incorrect answers.


# include <stdio.h> 
# include <gsl/gsl_sf_bessel.h> 
int main (void)
{
double x = 5.0; 
double y = gsl_sf_bessel_j0 (x); 
printf ("JO(%g) =  %.18e\n", x , y);
return(0);
}

What you get: *JO(5) =  -1.917848549326277019e-01*.
What you expect (see documentation): *JO(5) =  -1.775967713143382920e-01*.
When I replace *gsl_sf_bessel_j0* with *gsl_sf_bessel_J0* I get *JO(5) = 
-1.775967713143382642e-01* which is close to the desired output.


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