[Bug math/6795] New: hypot() does not set errno consistently on error

[Bug math/6795] New: hypot() does not set errno consistently on error

[mtk dot manpages at gmail dot com]

hypot() raises an exception for underflow and overflow, but only sets errno to
ERANGE for the overflow case.  It should set errno also for the underflow case.

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: hypot() does not set errno consistently on 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=6795

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[Bug math/6795] hypot() does not set errno consistently on error

[mtk dot manpages at gmail dot com]

------- Additional Comments From mtk dot manpages at gmail dot com  2008-07-31 09:56 -------
Created an attachment (id=2857)
 --> (http://sourceware.org/bugzilla/attachment.cgi?id=2857&action=view)
test program

Sample runs demonstrating the problem:

$ /tmp/mt_hypot dbl_max dbl_max
errno == ERANGE
fetestexcept() says:  FE_OVERFLOW FE_INEXACT
hypot(1.79769313486231571e+308,1.79769313486231571e+308)=inf
ERANGE FE_OVERFLOW +inf

$ /tmp/mt_hypot subnormal:20 subnormal:20
errno == 0
fetestexcept() says:  FE_UNDERFLOW FE_INEXACT
hypot(2.12199579096527232e-314,2.12199579096527232e-314)=3.00095522690537735e-314

0 FE_UNDERFLOW subnormal


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http://sourceware.org/bugzilla/show_bug.cgi?id=6795

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[Bug math/6795] hypot() does not set errno consistently on error

[jsm28 at gcc dot gnu.org]

http://sourceware.org/bugzilla/show_bug.cgi?id=6795

Joseph Myers <jsm28 at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|aj at suse dot de           |unassigned at sourceware
                   |                            |dot org

--- Comment #2 from Joseph Myers <jsm28 at gcc dot gnu.org> 2012-03-01 02:28:33 UTC ---
Confirmed with current sources on both x86 and x86_64.

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[Bug math/6795] hypot() does not set errno consistently on error

[jsm28 at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=6795

Joseph Myers <jsm28 at gcc dot gnu.org> changed:

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

--- Comment #3 from Joseph Myers <jsm28 at gcc dot gnu.org> ---
It's now documented that errno is only intended to be set to ERANGE for
underflow to 0, not for underflow to subnormals, and hypot can't underflow to
0.

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