Re: [eigen] sse transcendental functions |

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*To*: eigen@xxxxxxxxxxxxxxxxxxx*Subject*: Re: [eigen] sse transcendental functions*From*: Gael Guennebaud <gael.guennebaud@xxxxxxxxx>*Date*: Thu, 26 Mar 2009 16:40:29 +0100*Dkim-signature*: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:in-reply-to:references :date:message-id:subject:from:to:content-type :content-transfer-encoding; bh=83K0iUGSH1S0SCqJf0uZjQp2cWz2RgU3woYpYra0FeE=; b=Zc17QnYE8QjSsDokaiD1TMQdRwSWW2o2Kqdvn9qW3JN+X4U81iZW/MmKYnvtv2dVom k1HI+Mq5JDUvppibT6+RrJcjmLsTrrdZiHgril5TsDJ2sjcBUAy5zXslaOaxAZoFwNN0 DXjzAE1PUWAjHxMsrBcg/a+bBtBOJkm5c3GKw=*Domainkey-signature*: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type:content-transfer-encoding; b=e+f6kapsDCCT3QkBLqZEYFETM1oH16l1aNzqQIEyGw7GUJNYQHC53N7q42N+UKEL8P HbRaEjDF2Qihlnz5U2E+8bavDL1f+QB/k2LAW8S00uHUfKjyPZxbZClWoA3OyMshjbjj /EAXOTZlTAZRY9MY367aVNSqJBOSoEG4EF5Ds=

On Thu, Mar 26, 2009 at 2:11 PM, Rohit Garg <rpg.314@xxxxxxxxx> wrote: > I was looking through the svn log and i found this > > r944892 | ggael | 2009-03-26 18:20:24 +0530 (Thu, 26 Mar 2009) | 6 lines > > * enable vectorization of sin, cos, etc. by default with an option to > disable them (-DEIGEN_FAST_MATH=0) > * add a specialization of MatrixBase::operator*(RealScalar) for fast > "matrix of complex" times scalar products (even more useful for > autodiff scalar types) > > 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. > -- > Rohit Garg > > http://rpg-314.blogspot.com/ > > Senior Undergraduate > Department of Physics > Indian Institute of Technology > Bombay > > >

**Follow-Ups**:**Re: [eigen] sse transcendental functions***From:*Rohit Garg

**References**:**[eigen] sse transcendental functions***From:*Rohit Garg

**Re: [eigen] sse transcendental functions***From:*Gael Guennebaud

**Re: [eigen] sse transcendental functions***From:*Rohit Garg

**Re: [eigen] sse transcendental functions***From:*Gael Guennebaud

**Re: [eigen] sse transcendental functions***From:*Rohit Garg

**Re: [eigen] sse transcendental functions***From:*Rohit Garg

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