Re: [eigen] Re: SSE square root |

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*To*: eigen@xxxxxxxxxxxxxxxxxxx*Subject*: Re: [eigen] Re: SSE square root*From*: Christian Mayer <mail@xxxxxxxxxxxxxxxxx>*Date*: Fri, 27 Mar 2009 10:20:31 +0100*Dkim-signature*: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:sender:message-id:date:from :reply-to:user-agent:mime-version:to:subject:references:in-reply-to :x-enigmail-version:content-type:content-transfer-encoding; bh=tILlf0nTOTrzwjZ24YpniXBTEa4dUfPoyH8ZFFDuGqA=; b=PVs8aeDHD7ElLiPuaWg+/4fOZzHqCaGMXyLE6DFtGzfz4RJ0kjgWOnypByBgN28D2l ELxXM5D3/3VrHRiXyOLjiychU5EjVI0EsYk6Oyod3FmIsnzwueYQxCxgeG6yqZcXF0vw pZSGQApcHOZsgHOhv+PKXY3wEdiyfzsYVA+Wg=*Domainkey-signature*: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=sender:message-id:date:from:reply-to:user-agent:mime-version:to :subject:references:in-reply-to:x-enigmail-version:content-type :content-transfer-encoding; b=aj8wLzvbhwpUSHYR+8507mNuIVJvwVXILL2j+D4NGr144jI1GhRTYta/3pHSzVjRZn ViaojEbkW7v3BNZHj961D1l6Jlh5dSzBqCZrF1VYf6ZNRfDd4t7h73SauDIl0Ct/RUN5 52L+rN4m0xsr962pepptYzFjnDK0x+NKESsiM=

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 This looks lika candidate for a templated version that takes the number of iterations as the template parameter... Rohit Garg schrieb: > I compared the absolute accuracy in the [0,1] interval and I found > that only one iteration is enough for accuracy purposes, which seems > about right. > > On Fri, Mar 27, 2009 at 1:02 PM, Rohit Garg <rpg.314@xxxxxxxxx> wrote: >> This file has my sse float implementation for square root. The SSE >> square root instruction has only 12 bits of precision so extra >> iterations of Newton Raphson may be neccessary. How many of the are >> neccessary, I don't know. the max error I was getting was O(1e-8) in >> [0,1]. The cephes implementation has square root only for limited >> range. They do some other hacks to take care of range. I'll look into >> implementing those later. For now, this should be an acceptable for >> the fast implementations of square root atleast. >> >> Regards, >> >> -- >> Rohit Garg >> >> http://rpg-314.blogspot.com/ >> >> Senior Undergraduate >> Department of Physics >> Indian Institute of Technology >> Bombay >> > > > -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (GNU/Linux) iEYEAREIAAYFAknMml8ACgkQoWM1JLkHou368gCfb8zF8tx8rTExdofW24Z6Xe/m S/YAnj71fu2J7LWyaqB7tOOglY15E4Ng =kTgD -----END PGP SIGNATURE-----

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