[Bug math/13381] rounding problem wih sincosl

["gastineau at imcce dot fr" <sourceware-bugzilla at sourceware dot org>]

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

--- Comment #9 from gastineau at imcce dot fr 2011-12-22 19:31:39 UTC ---
The current glibc documentation says :

In many applications where sin and cos are used, the sine and cosine of the
same angle are needed at the same time. It is more efficient to compute them
simultaneously, so the library provides a 
function to do that.

â Function: void sincos (double x, double *sinx, double *cosx)
â Function: void sincosf (float x, float *sinx, float *cosx)
â Function: void sincosl (long double x, long double *sinx, long double *cosx)
These functions return the sine of x in *sinx and the cosine of x in *cos,
where x is given in radians. Both values, *sinx and *cosx, are in the range of
-1 to 1.

This function is a GNU extension. Portable programs should be prepared to cope
with its absence.



So, if it's a GNU extension, it's not of the responsability of the user to
check that it gives a different result, as the documentation says no thing
about the implementation.

MickaÃl




Le 22/12/11 18:45, drepper.fsp at gmail dot com a Ãcrit :
> http://sourceware.org/bugzilla/show_bug.cgi?id=13381
>
> Ulrich Drepper<drepper.fsp at gmail dot com>  changed:
>
>             What    |Removed                     |Added
> ----------------------------------------------------------------------------
>               Status|REOPENED                    |RESOLVED
>           Resolution|                            |INVALID
>
> --- Comment #8 from Ulrich Drepper<drepper.fsp at gmail dot com>  2011-12-22 17:45:01 UTC ---
> If you don't understand how computers work then don't bother other people.  The
> function is implemented by a single instruction.  It's entire Intel's
> responsibility to provide the result.
>

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