Date: Tue, 18 Sep 2012 22:48:34 -0500 From: Stephen Montgomery-Smith <stephen@missouri.edu> To: Bruce Evans <brde@optusnet.com.au> Cc: freebsd-numerics@freebsd.org Subject: Re: Complex arg-trig functions Message-ID: <50594092.6000302@missouri.edu> In-Reply-To: <20120918150551.Y820@besplex.bde.org> References: <5017111E.6060003@missouri.edu> <5048D00B.8010401@missouri.edu> <504D3CCD.2050006@missouri.edu> <504FF726.9060001@missouri.edu> <20120912191556.F1078@besplex.bde.org> <20120912225847.J1771@besplex.bde.org> <50511B40.3070009@missouri.edu> <20120913204808.T1964@besplex.bde.org> <5051F59C.6000603@missouri.edu> <20120914014208.I2862@besplex.bde.org> <50526050.2070303@missouri.edu> <20120914212403.H1983@besplex.bde.org> <50538E28.6050400@missouri.edu> <20120915231032.C2669@besplex.bde.org> <50548E15.3010405@missouri.edu> <5054C027.2040008@missouri.edu> <5054C200.7090307@missouri.edu> <20120916041132.D6344@besplex.bde.org> <50553424.2080902@missouri.edu> <20120916134730.Y957@besplex.bde.org> <5055ECA8.2080008@missouri.edu> <20120917022614.R2943@besplex.bde.org> <50562213.9020400@missouri.edu> <20120917060116.G3825@besplex.bde.org> <50563C57.60806@missouri.edu> <20120918012459.V5094@besplex.bde.org> <5057A932.3000603@missouri.edu> <20120918150551.Y820@besplex.bde.org>
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On 09/18/2012 01:19 AM, Bruce Evans wrote: > On Mon, 17 Sep 2012, Stephen Montgomery-Smith wrote: >> I don't think your code works. It should be ry = atan2f(2, -ay) / 2, >> not ry = atan2f(2, ay) / 2. > > Only logically. As I explained, the negation makes no difference to the > result, but of course takes longer, so I removed it. No, they give different results. atan2(y,x) = Pi - atan2(y,-x) if y is positive.
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