Use of C99 extra long double math functions after r236148

[Peter Jeremy]

On 2012-Jul-22 16:10:56 -0700, Steve Kargl <sgk at troutmask.apl.washington.edu> wrote:
>The above isn't necessarily true.  The Fortran standards from
>2003 and 2008, very care about NaN.  Under certain conditions,
>if one has something like 
>
>   x = sin(NaN)
>
>in Fortran, then the returned NaN must be the one in the function
>call.

Even if it was a SNaN?  My understanding is that SNaN should be
quietened if they are used in any further floating point operations.

>  Having libm, do
>
>   if (x == NaN)
>      return (x + x);
>
>does/may not return the correct NaN.

I presume you mean
    if (isnan(x))
        return (x + x);

Do you have a test case that shows that?  As far as I can tell, all
the FPUs I have access to will return a quietened variant of the
input NaN in this case (ie, only the signalling bit is altered).

-- 
Peter Jeremy
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