lib/libm/src/s_ctanh.c

   1 /*      $OpenBSD: s_ctanh.c,v 1.5 2013/03/28 18:09:38 martynas Exp $    */
   2 /*
   3  * Copyright (c) 2008 Stephen L. Moshier <steve@moshier.net>
   4  *
   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.
   8  *
   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.
  16  */
  17
  18 /*                                                      ctanh
  19  *
  20  *      Complex hyperbolic tangent
  21  *
  22  *
  23  *
  24  * SYNOPSIS:
  25  *
  26  * double complex ctanh();
  27  * double complex z, w;
  28  *
  29  * w = ctanh (z);
  30  *
  31  *
  32  *
  33  * DESCRIPTION:
  34  *
  35  * tanh z = (sinh 2x  +  i sin 2y) / (cosh 2x + cos 2y) .
  36  *
  37  * ACCURACY:
  38  *
  39  *                      Relative error:
  40  * arithmetic   domain     # trials      peak         rms
  41  *    IEEE      -10,+10     30000       1.7e-14     2.4e-16
  42  *
  43  */
  44
  45 #include <complex.h>
  46 #include <float.h>
  47 #include <math.h>
  48
  49 double complex
  50 ctanh(double complex z)
  51 {
  52         double complex w;
  53         double x, y, d;
  54
  55         x = creal(z);
  56         y = cimag(z);
  57         d = cosh (2.0 * x) + cos (2.0 * y);
  58         w = sinh (2.0 * x) / d  +  (sin (2.0 * y) / d) * I;
  59         return (w);
  60 }
  61
  62 #if     LDBL_MANT_DIG == 53
  63 __strong_alias(ctanhl, ctanh);
  64 #endif  /* LDBL_MANT_DIG == 53 */