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Subject: [Bug math/14811] New: Spurious underflows from pow results very close to 1
Date: Tue, 06 Nov 2012 16:52:00 -0000
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http://sourceware.org/bugzilla/show_bug.cgi?id=14811

             Bug #: 14811
           Summary: Spurious underflows from pow results very close to 1
           Product: glibc
           Version: 2.16
            Status: NEW
          Severity: normal
          Priority: P2
         Component: math
        AssignedTo: unassigned@sourceware.org
        ReportedBy: jsm28@gcc.gnu.org
    Classification: Unclassified


Various pow implementations have internal underflows in the internal
computation of y * log (x) when that is very small.  For example, the following
all raise spurious underflow exceptions on x86_64 (and return the correct
answer 1): powf (1.01f, 0x1p-149f), pow (1.01, 0x1p-1074), powl (1.01L,
0x1p-16445L).

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