|Re: [eigen] sse transcendental functions|
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- To: eigen@xxxxxxxxxxxxxxxxxxx
- Subject: Re: [eigen] sse transcendental functions
- From: Rohit Garg <rpg.314@xxxxxxxxx>
- Date: Thu, 26 Mar 2009 22:39:36 +0530
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>> 1) It could be obvious but what does the DEIGEN_FAST_MATH macro do?
> this is explained in the doxy doc, just on top of EIGEN_FAST_MATH,
> basically it allows you to disable some optimizations which might
> degrades the accuracy
>> 2) do you feel there is place for fast implementations of such
>> transcendental functions in eigen? I think we should clearly advertise
>> in the documentation that the SSE version is for 'fast-operations' as
>> seems to be the case. BTW, automagically enabling these when the user
>> compiles with -ffast-math would be cool.
> well, currently the only problem of accuracy is for sin/cos and single
> precision floating point values out of the range [-8000 : 8000]. In
> such cases, the error is still lower than taking the same value modulo
> 2pi and then call the glibc sin/cos function. So, really, I think, it
> is safe to enable them by default.
>> 3) any particular reason why the sincos4f from the Julian's sources
>> hasn't made it in yet?
> because currently there is no sincos function in eigen.
Well that's exactly what I was asking, sincos function has been
implemented by Julian, then why was it not committed. AFAICS, is it
because the return values are passed by pointer to it?
Department of Physics
Indian Institute of Technology