[Bug math/13239] New: logl returns wrong values on Linux/SPARC in 64-bit mode

["bruno at clisp dot org" <sourceware-bugzilla at sourceware dot org>]

http://sourceware.org/bugzilla/show_bug.cgi?id=13239

             Bug #: 13239
           Summary: logl returns wrong values on Linux/SPARC in 64-bit
                    mode
           Product: glibc
           Version: 2.8
            Status: NEW
          Severity: normal
          Priority: P2
         Component: math
        AssignedTo: aj@suse.de
        ReportedBy: bruno@clisp.org
    Classification: Unclassified


The logl() function from -lm returns wrong values on Linux 2.6.26 with
glibc 2.7.

The test program computes logl(0.6). The multiprecision value is
-0.51082562376599068320551409630366193487811079644...

================================ foo.c ===============================
#include <math.h>
#include <stdio.h>
volatile long double x;
long double y;
int
main ()
{
  x = 0.6L;
  y = logl (x);
  printf ("logl(0.6) = %.16g\n          = %.32Lg\n", (double)y, y);
  if (!(y >= -0.5108256238L && y <= -0.5108256237L))
    {
      printf ("not within expected bounds!\n");
      return 1;
    }
  return 0;
}
======================================================================

Result on Linux/SPARC in 64-bit mode:
$ gcc -m64 foo.c -lm 
$ ./a.out 
logl(0.6) = 2977044471.308746
          = 2977044471.3087464477296220972981
not within expected bounds!

Result on Linux/SPARC in 32-bit mode:
$ gcc -m32 foo.c -lm 
$ ./a.out 
logl(0.6) = -0.5108256237659907
          = -0.51082562376599068320551409630366

Result on Linux/x86_64:
logl(0.6) = -0.5108256237659907
          = -0.51082562376599068319294252860097

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