[Bug math/6810] New: tgamma() does not set errno for underflow error

[Bug math/6810] New: tgamma() does not set errno for underflow error

[mtk dot manpages at gmail dot com]

tgamma() correctly sets errno and raises an exception for an overflow error. 
However, for an underflow error, it only raises an exception -- errno is not
set; errno should be set to ERANGE for this 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: tgamma() does not set errno for underflow 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=6810

------- You are receiving this mail because: -------
You are on the CC list for the bug, or are watching someone who is.

[Bug math/6810] tgamma() does not set errno for underflow error

[mtk dot manpages at gmail dot com]

------- Additional Comments From mtk dot manpages at gmail dot com  2008-07-31 13:53 -------
Created an attachment (id=2882)
 --> (http://sourceware.org/bugzilla/attachment.cgi?id=2882&action=view)
test program

Sample runs demonstrating the problem:

$ /tmp/mt_tgamma 1e3
errno == ERANGE
fetestexcept() says:  FE_OVERFLOW FE_INEXACT
tgamma(1.00000000000000000e+03)=inf
ERANGE FE_OVERFLOW +inf

$ /tmp/mt_tgamma -- -100000.5
errno == 0
fetestexcept() says:  FE_UNDERFLOW FE_INEXACT
tgamma(-1.00000500000000000e+05)=-0.00000000000000000e+00
0 FE_UNDERFLOW -0


-- 


http://sourceware.org/bugzilla/show_bug.cgi?id=6810

------- You are receiving this mail because: -------
You are on the CC list for the bug, or are watching someone who is.