[Bug math/6807] New: y0(), y1(), yn() do not raise exception and give wrong errno for pole error

["mtk dot manpages at gmail dot com" <sourceware-bugzilla at sourceware dot org>]

The POSIX.1 spec of y0(), y1(), yn() says:

==
Pole Error
    The value of x is zero.

    If the integer expression (math_errhandling & MATH_ERRNO) is non-zero, then
errno shall be set to [ERANGE]. If the integer expression (math_errhandling &
MATH_ERREXCEPT) is non-zero, then the divide-by-zero floating-point exception
shall be raised.
==

For a pole error, GNU's y0(), y1(), yn() set errno to EDOM, and do not raise an
IEEE exception.  This is wrong on both counts.  errno should be set to ERANGE,
and an FE_DIVBYZERO exception should occur.

Note: the POLE ERROR text was only added to POSIX.1-2001 for TC2 (i.e.,
POSIX.1-2004; before that, this case was specified as a RANGE ERROR (which is
mathematically incorrect).

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: y0(), y1(), yn() do not raise exception and give wrong
                    errno for pole 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=6807

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