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From: "jsm28 at gcc dot gnu.org" <sourceware-bugzilla@sourceware.org> To: glibc-bugs@sources.redhat.com Subject: [Bug math/14793] New: Further spurious underflows from fma when a * b is small Date: Thu, 01 Nov 2012 00:53:00 -0000 [thread overview] Message-ID: <bug-14793-131@http.sourceware.org/bugzilla/> (raw) http://sourceware.org/bugzilla/show_bug.cgi?id=14793 Bug #: 14793 Summary: Further spurious underflows from fma when a * b is small Product: glibc Version: 2.16 Status: NEW Severity: normal Priority: P2 Component: math AssignedTo: unassigned@sourceware.org ReportedBy: jsm28@gcc.gnu.org Classification: Unclassified Given my patch http://sourceware.org/ml/libc-alpha/2012-11/msg00001.html for bug 14784 there are still some underflows from fma (a, b, c) when a * b is small, because the logic has a gap of two exponents between the cases when a * b is so small that its exact value doesn't matter, and the cases where the scaling-up for small a * b is enough to avoid underflow when computing the Dekker multiplication. Example, on x86 or x86_64: fmal (0x1.0000000000000002p-16382L, 0x1.0000000000000002p-66L, 0x1p16383L) raises a spurious underflow exception. -- Configure bugmail: http://sourceware.org/bugzilla/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are on the CC list for the bug.
next reply other threads:[~2012-11-01 0:53 UTC|newest] Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top 2012-11-01 0:53 jsm28 at gcc dot gnu.org [this message] 2012-11-05 22:04 ` [Bug math/14793] " jsm28 at gcc dot gnu.org 2012-11-06 14:14 ` jsm28 at gcc dot gnu.org 2014-06-14 11:16 ` fweimer at redhat dot com
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