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catanf.c revision 1.1 
      1 /* $NetBSD: catanf.c,v 1.1 2007/08/20 16:01:32 drochner Exp $ */
      2 
      3 /*-
      4  * Copyright (c) 2007 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software written by Stephen L. Moshier.
      8  * It is redistributed by the NetBSD Foundation by permission of the author.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     29  * POSSIBILITY OF SUCH DAMAGE.
     30  */
     31 
     32 #include "../src/namespace.h"
     33 #include <complex.h>
     34 #include <math.h>
     35 #include "cephes_subrf.h"
     36 
     37 #ifdef __weak_alias
     38 __weak_alias(catanf, _catanf)
     39 #endif
     40 
     41 #define MAXNUMF 1.0e38F
     42 
     43 float complex
     44 catanf(float complex z)
     45 {
     46 	float complex w;
     47 	float a, t, x, x2, y;
     48 
     49 	x = crealf(z);
     50 	y = cimagf(z);
     51 
     52 	if ((x == 0.0f) && (y > 1.0f))
     53 		goto ovrf;
     54 
     55 	x2 = x * x;
     56 	a = 1.0f - x2 - (y * y);
     57 	if (a == 0.0f)
     58 		goto ovrf;
     59 
     60 	t = 0.5f * atan2f(2.0f * x, a);
     61 	w = _redupif(t);
     62 
     63 	t = y - 1.0f;
     64 	a = x2 + (t * t);
     65 	if (a == 0.0f)
     66 		goto ovrf;
     67 
     68 	t = y + 1.0f;
     69 	a = (x2 + (t * t))/a;
     70 	w = w + (0.25f * logf(a)) * I;
     71 	return w;
     72 
     73 ovrf:
     74 #if 0
     75 	mtherr ("catan", OVERFLOW);
     76 #endif
     77 	w = MAXNUMF + MAXNUMF * I;
     78 	return w;
     79 }
     80