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ctan.c revision 1.1 
      1 /* $NetBSD: ctan.c,v 1.1 2007/08/20 16:01:37 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_subr.h"
     36 
     37 #define MAXNUM 1.0e308
     38 
     39 double complex
     40 ctan(double complex z)
     41 {
     42 	double complex w;
     43 	double d;
     44 
     45 	d = cos(2.0 * creal(z)) + cosh(2.0 * cimag(z));
     46 
     47 	if (fabs(d) < 0.25)
     48 		d = _ctans(z);
     49 
     50 	if (d == 0.0) {
     51 		/* mtherr ("ctan", OVERFLOW); */
     52 		w = MAXNUM + MAXNUM * I;
     53 		return w;
     54 	}
     55 
     56 	w = sin(2.0 * creal(z)) / d + (sinh(2.0 * cimag(z)) / d) * I;
     57 	return w;
     58 }
     59