Sine and Cosine Accuracy

[Menezes, Evandro]

Scott, 

> I still maintain that hardware fsin and fcos are valid and 
> valuable for certain classes of applications,

I agree.  I've just been trying to demonstrate that your test doesn't check sin and cos accuracies, but that sin^2 + cos^2 == 1.  If I had a sin that always returned 1.0 and a cos that always returned 0.0 they would pass your test. :-)

> and that we 
> need better options and documentation -- both of which I'm 
> more than happy to work on. I look forward to your future comments.

By all means, there are many holes in GCC documentation and you've probably tripped at one.  

Yet, I think that enabling x87 transcendentals on x86 only with -funsafe-math-optimizations makes sense, because they're anything but safe: "(a) assume that arguments and results are valid and (b) may violate IEEE or ANSI standards."

And it doesn't make sense to enable them on x86_64 because they're not more optimal than the SSE routines.

Regards,


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Evandro Menezes            AMD               Austin, TX