[Bug math/6784] New: fmod() inconsistently sets errno on domain error

[Bug math/6784] New: fmod() inconsistently sets errno on domain error

[mtk dot manpages at gmail dot com]

The calls fmod(x, 0) and fmod(inf, y) should both result in a domain
error.

For both of these calls, an invalid exception is correctly raised.

However, errno is not set consistently.  fmod(x, 0) does (correctly) set
errno to EDOM.  However, fmod(inf, y) does not set errno; it should do so.

Background: 
On error, many glibc math functions both set errno and raise an exception
(fetestexcept(3)).  For example, the following  function all do this: acos(),
asin(), cosh(), sinh(), acosh(), asinh(), exp(), exp2(), ldexp(), log(),
log10(), log2().  However, there is much inconsistency.  Some functions raise an
exception, but don't set errno.  Some functions set errno for some errors, but
not others.  A few set errno, but don't raise an exception.  This series of bug
reports documents deviations from what I consider the ideal: all functions
should BOTH set errno AND raise an exception for all errors.

All of these reports relate to tests on glibc 2.8 (as provided by SUSE 11.0).

-- 
           Summary: fmod() inconsistently sets errno on domain error
           Product: glibc
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: math
        AssignedTo: aj at suse dot de
        ReportedBy: mtk dot manpages at gmail dot com
                CC: glibc-bugs at sources dot redhat dot com


http://sourceware.org/bugzilla/show_bug.cgi?id=6784

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[Bug math/6784] fmod() inconsistently sets errno on domain error

[mtk dot manpages at gmail dot com]

------- Additional Comments From mtk dot manpages at gmail dot com  2008-07-31 08:46 -------
Created an attachment (id=2849)
 --> (http://sourceware.org/bugzilla/attachment.cgi?id=2849&action=view)
test program

See also http://sourceware.org/bugzilla/show_bug.cgi?id=6783

sample runs showing problem.  Note that EDOM is set in one case, but not the
other.

$ /tmp/mt_fmod -- inf 1
errno == 0
fetestexcept() says:  FE_INVALID
fmod(inf,1.00000000000000000e+00)=nan
0 FE_INVALID nan

$ /tmp/mt_fmod -- 1 0
errno == EDOM
fetestexcept() says:  FE_INVALID
fmod(1.00000000000000000e+00,0.00000000000000000e+00)=nan
EDOM FE_INVALID nan

-- 


http://sourceware.org/bugzilla/show_bug.cgi?id=6784

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[Bug math/6784] fmod() inconsistently sets errno on domain error

[mtk dot manpages at gmail dot com]

------- Additional Comments From mtk dot manpages at gmail dot com  2010-09-11 15:47 -------
This bug was fixed in glibc 2.10. The man page is updated for man-pages-2.37.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED


http://sourceware.org/bugzilla/show_bug.cgi?id=6784

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