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- To: eigen@xxxxxxxxxxxxxxxxxxx
- Subject: Re: [eigen] sse asin implementation
- From: Benoit Jacob <jacob.benoit.1@xxxxxxxxx>
- Date: Tue, 31 Mar 2009 18:49:12 +0200
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2009/3/31 Rohit Garg <rpg.314@xxxxxxxxx>:
> For general exponentiation, I think a cheap and easy route would be
> just exp(b*log(a))
>
> I looked at the cephes library implementation of pow and they do a lot
> of hacks just to get 3 bits of precision. In the use case that you
> have cited, I think it's better to just have the above implementation.
> It is certainly good enough for the -ffast-math case.
OK, seems sensible. But I thought the main justification for a simd
pow() would be performance, that it could be faster than the above
formula. If that's not the case then sure, I agree with you.
>
> BTW, what do you think of enabling the fast math paths in eigen when
> just -ffast-math is supplied to gcc. It can be detected by the
> __FAST_MATH__ macro.
That seems like a good idea! Let's see what Gael thinks.
Cheers,
Benoit