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From: "JoshuaHopp at web dot de" <sourceware-bugzilla@sourceware.org> To: glibc-bugs@sources.redhat.com Subject: [Bug math/14759] New: Most functions in math.h not correctly rounded Date: Wed, 24 Oct 2012 08:08:00 -0000 [thread overview] Message-ID: <bug-14759-131@http.sourceware.org/bugzilla/> (raw) http://sourceware.org/bugzilla/show_bug.cgi?id=14759 Bug #: 14759 Summary: Most functions in math.h not correctly rounded Product: glibc Version: 2.15 Status: NEW Severity: normal Priority: P2 Component: math AssignedTo: unassigned@sourceware.org ReportedBy: JoshuaHopp@web.de Classification: Unclassified Host: x86_64 Target: x86_64 Build: linux-gnu Most functions in math.h do not use correct rounding. Example: //--- snip --- #include <math.h> #include <fenv.h> #include <assert.h> int main() { double x = 1.0; // 1.0 is exact fesetround(FE_DOWNWARD); double a = asin(x); fesetround(FE_UPWARD); double b = asin(x); // asin(1) == pi/2, which is not exactly representable // so, assuming correct rounding, a should be less than b assert(a < b); } //--- snap --- Compile with "gcc -lm" (or even "gcc -lm -ffloat-store -frounding-math"). Run the example: main: Assertion `a < b' failed. Similar results can be obtained with exp, cos, acos, atan, sinh, cosh, atanh, asinh and acosh. ------ Kernel version: 3.5.2-1.fc17 gcc version 4.7.2 20120921 (Red Hat 4.7.2-2) (GCC) GNU ld version 2.22.52.0.1-10.fc17 20120131 -- 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:[~2012-10-24 8:08 UTC|newest] Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top 2012-10-24 8:08 JoshuaHopp at web dot de [this message] 2012-10-24 12:39 ` [Bug math/14759] " jsm28 at gcc dot gnu.org 2012-10-24 12:42 ` jsm28 at gcc dot gnu.org 2012-10-24 12:44 ` jsm28 at gcc dot gnu.org 2012-10-24 12:44 ` jsm28 at gcc dot gnu.org 2013-08-27 7:58 ` bagnara at cs dot unipr.it 2013-11-28 22:38 ` jsm28 at gcc dot gnu.org 2014-01-29 16:35 ` jsm28 at gcc dot gnu.org 2014-06-14 11:18 ` fweimer at redhat dot com
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