[Bug math/4108] New: erfcf returns incorrectly rounded results compared to erfc

[myles at peakstreaminc dot com]

In the attached program results from erfc are compared with results from erfcf
and large differences are flagged. The errors occur for values near 4.0 and 8.0,
but slightly under.

Two examples:

x: 3.9311595 (407b981e)  float(erfc): 2.7055004e-08 (32e86695)  erfcf: 2.705503e
-08 (32e866a4)  diff: 2.6645353e-14 (45 ULP)

x: 7.9999866 (40ffffe4)  float(erfc): 1.1226714e-29 (f63b46e)  erfcf: 1.1226756e
-29 (f63b4a7)  diff: 4.2882034e-35 (114 ULP)


It is possible the values for erfc are incorrect, as I don't have another source
to check that.

Also happens on x86_64-redhat-linux

-- 
           Summary: erfcf returns incorrectly rounded results compared to
                    erfc
           Product: glibc
           Version: 2.3.4
            Status: NEW
          Severity: normal
          Priority: P2
         Component: math
        AssignedTo: aj at suse dot de
        ReportedBy: myles at peakstreaminc dot com
                CC: glibc-bugs at sources dot redhat dot com
 GCC build triplet: i386-redhat-linux
  GCC host triplet: i386-redhat-linux
GCC target triplet: i386-redhat-linux


http://sourceware.org/bugzilla/show_bug.cgi?id=4108

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