[Bug math/13381] rounding problem wih sincosl

["martyn.j.corden at intel dot com" <sourceware-bugzilla@sourceware.org>]

http://sourceware.org/bugzilla/show_bug.cgi?id=13381

martyn.j.corden at intel dot com changed:

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--- Comment #13 from martyn.j.corden at intel dot com 2012-01-09 20:02:37 UTC ---
Yes, this is likely an issue of slightly different algorithms in the math
library. The main purpose of a sincos function is to give results more
quickly/efficiently that two separate calls to sin and cos, and that might be
better achieved with a different algorithm.
      The same issue arose in the math library provided with the Intel
compiler, libimf. Following a customer report, a change was made for version
12.1 of the Intel compiler, (in Intel Composer XE 2011 SP1), so that sincosl
would return the same results as calls to sinl and cosl. Presumably, similar
changes could be made to the GNU libm if this is felt to be an important issue,
otherwise the sincos documentation should be updated to warn of the potential
difference.  If you have access to Intel’s libimf, it is also possible to link
to it when compiling with gcc, to work around this issue.

Martyn Corden      (Intel Developer Support)

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