src/complex/ctanhf.c

   1 /* origin: FreeBSD /usr/src/lib/msun/src/s_ctanhf.c */
   2 /*-
   3  * Copyright (c) 2011 David Schultz
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice unmodified, this list of conditions, and the following
  11  *    disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  17  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  18  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  19  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  20  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  21  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  22  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  23  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  24  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  25  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  26  */
  27 /*
  28  * Hyperbolic tangent of a complex argument z.  See s_ctanh.c for details.
  29  */
  30
  31 #include "libm.h"
  32
  33 float complex ctanhf(float complex z)
  34 {
  35         float x, y;
  36         float t, beta, s, rho, denom;
  37         uint32_t hx, ix;
  38
  39         x = crealf(z);
  40         y = cimagf(z);
  41
  42         GET_FLOAT_WORD(hx, x);
  43         ix = hx & 0x7fffffff;
  44
  45         if (ix >= 0x7f800000) {
  46                 if (ix & 0x7fffff)
  47                         return CMPLXF(x, (y == 0 ? y : x * y));
  48                 SET_FLOAT_WORD(x, hx - 0x40000000);
  49                 return CMPLXF(x, copysignf(0, isinf(y) ? y : sinf(y) * cosf(y)));
  50         }
  51
  52         if (!isfinite(y))
  53                 return CMPLXF(ix ? y - y : x, y - y);
  54
  55         if (ix >= 0x41300000) { /* x >= 11 */
  56                 float exp_mx = expf(-fabsf(x));
  57                 return CMPLXF(copysignf(1, x), 4 * sinf(y) * cosf(y) * exp_mx * exp_mx);
  58         }
  59
  60         t = tanf(y);
  61         beta = 1.0 + t * t;
  62         s = sinhf(x);
  63         rho = sqrtf(1 + s * s);
  64         denom = 1 + beta * s * s;
  65         return CMPLXF((beta * rho * s) / denom, t / denom);
  66 }