1 /* $OpenBSD: s_catanf.c,v 1.2 2010/07/18 18:42:26 guenther Exp $ */
3 * Copyright (c) 2008 Stephen L. Moshier <steve@moshier.net>
5 * Permission to use, copy, modify, and distribute this software for any
6 * purpose with or without fee is hereby granted, provided that the above
7 * copyright notice and this permission notice appear in all copies.
9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
20 * Complex circular arc tangent
26 * float complex catanf();
40 * Re w = - arctan(-----------) + k PI
46 * Im w = - log(------------)
50 * Where k is an arbitrary integer.
57 * arithmetic domain # trials peak rms
58 * IEEE -10,+10 30000 2.3e-6 5.2e-8
65 #define MAXNUMF 1.0e38F
67 static const double DP1 = 3.140625;
68 static const double DP2 = 9.67502593994140625E-4;
69 static const double DP3 = 1.509957990978376432E-7;
84 i = t; /* the multiple */
86 t = ((x - t * DP1) - t * DP2) - t * DP3;
91 catanf(float complex z)
99 if((x == 0.0f) && (y > 1.0f))
103 a = 1.0f - x2 - (y * y);
107 t = 0.5f * atan2f(2.0f * x, a);
116 a = (x2 + (t * t))/a;
117 w = w + (0.25f * logf (a)) * I;
121 /*mtherr( "catanf", OVERFLOW );*/
122 w = MAXNUMF + MAXNUMF * I;