[Bug math/2154] accuracy of cacoshl is bad.

[jsm28 at gcc dot gnu.org]

http://sourceware.org/bugzilla/show_bug.cgi?id=2154

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

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

--- Comment #2 from Joseph Myers <jsm28 at gcc dot gnu.org> 2012-02-22 22:22:26 UTC ---
The tests given in this bug take the double constants 0.3 and 0.4 and convert
them to long double.  The results of cacoshl appear to be within a few ULPs of
what is expected for those particular long double values, whereas the
expectations given in this testcase are the results for infinite-precision
constants 0.3 and 0.4 (as opposed to those for values rounded to 53 bits then
extended to 64 bits, or rounded directly to 64 bits) - and when your inputs
differ by 11 bits from what they were intended to be, 770 ULPs is hardly an
unexpected error.  So this is not a correct test and there is no sign of undue
inaccuracy here (I don't think it's yet expected for complex functions to be
last-bit-accurate correctly rounded).

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