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Failed to connect to MySQL: (1203) User howardkn already has more than 'max_user_connections' active connectionsPath: ...!news.mixmin.net!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: Michael S Newsgroups: comp.arch Subject: Re: Continuations Date: Mon, 22 Jul 2024 14:01:15 +0300 Organization: A noiseless patient Spider Lines: 29 Message-ID: <20240722140115.000058cf@yahoo.com> References: <47689j5gbdg2runh3t7oq2thodmfkalno6@4ax.com> <116d9j5651mtjmq4bkjaheuf0pgpu6p0m8@4ax.com> <7u7e9j5dthm94vb2vdsugngjf1cafhu2i4@4ax.com> <0f7b4deb1761f4c485d1dc3b21eb7cb3@www.novabbs.org> <277c774f1eb48be79cd148dfc25c4367@www.novabbs.org> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Injection-Date: Mon, 22 Jul 2024 13:00:46 +0200 (CEST) Injection-Info: dont-email.me; posting-host="c0390b39bf890723fb1576e1963acf04"; logging-data="76540"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1/pJ0gvfR0dg0s2HCvfO4OW1wXFaIXKPDI=" Cancel-Lock: sha1:YgHLP8W1eNY4adK0PuZybDK7BrE= X-Newsreader: Claws Mail 3.19.1 (GTK+ 2.24.33; x86_64-w64-mingw32) Bytes: 2598 On Fri, 19 Jul 2024 20:55:47 +0200 Terje Mathisen wrote: > MitchAlsup1 wrote: > > On Fri, 19 Jul 2024 14:16:01 +0000, Terje Mathisen wrote: > >> Back when I first looked at Invsqrt(), I did so because an > >> Computation Fluid Chemistry researcher from Sweden asked for help > >> speeding up his reciprocal calculations > >> (sqrt(1/(dx^2+dy^2+dz^2))), I found that by combining the 1/x and > >> the sqrt and doing three of them pipelind together (all the water > >> molecules having three atoms), his weeklong simulation runs ran in > >> half the time, on both PentiumPro and Alpha hardware. > > > > I, personally, have found many Newton-Raphson iterators that > > converge faster using 1/SQRT(x) than using the SQRT(x) equivalent. > > Yeah, that was eye-opening to me as well, to the level where I > consider the invsqrt() NR iteration as a mainstay, it can be useful > for both sqrt and 1/x as well. :-) > > Terje > What is this "SQRT(x) equivalent" all of you are talking about? I am not aware of any "direct" (i.e. not via RSQRT) NR-like method for SQRT that consists only of multiplicationa and additions. If it exists, I will be very interested to know.