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*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=s6lzVnRKPqXRJnAgDtCTFKs1rCaqL7/LoqMJ/hwYenk=; b=lOQXJixc8K1vGnDsXVhOWnlI1BNTG+kJJ7Wyv+ol5kQ1rA+fjSQJhhnqtBHAFH4ZSa BbN7SYpvP1w7ayBAhtsE5U7cRVxIrYKwi4Mc4AA1wdRCoqJCSQIGQMzJzf69H5UeQb2Q 05lLz6QBPXacq6tcca82wZJboBCHd2lGrpTC8=*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=EWJzBEDFWB4ZPhxq5XTmoF4FEmPveFJsV7HNm5lU5qMUJvRLx1YNpHLtUvxvfjOaf8 Jk2PAZiUKDjF1R+KWSzKGYIsu6BuT9DWKwUqaH1KoMgT6ObzDgWSSFuX9aOr6aDwplFS l0Og+/FFwgQcg198enQ3lqUUP3DjW3qyULLgY=

<snip> >> 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 Thanks. > >> 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. Ok. > >> 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? -- 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:*Gael Guennebaud

**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

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

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