gonzui

    1: /*      $OpenBSD: s_cpowf.c,v 1.2 2010/07/18 18:42:26 guenther 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: /*                                                      cpowf
   19:  *
   20:  *      Complex power function
   21:  *
   22:  *
   23:  *
   24:  * SYNOPSIS:
   25:  *
   26:  * float complex cpowf();
   27:  * float complex a, z, w;
   28:  *
   29:  * w = cpowf (a, z);
   30:  *
   31:  *
   32:  *
   33:  * DESCRIPTION:
   34:  *
   35:  * Raises complex A to the complex Zth power.
   36:  * Definition is per AMS55 # 4.2.8,
   37:  * analytically equivalent to cpow(a,z) = cexp(z clog(a)).
   38:  *
   39:  * ACCURACY:
   40:  *
   41:  *                      Relative error:
   42:  * arithmetic   domain     # trials      peak         rms
   43:  *    IEEE      -10,+10     30000       9.4e-15     1.5e-15
   44:  *
   45:  */
   46: 
   47: #include <complex.h>
   48: #include <math.h>
   49: 
   50: float complex
   51: cpowf(float complex a, float complex z)
   52: {
   53:         float complex w;
   54:         float x, y, r, theta, absa, arga;
   55: 
   56:         x = crealf(z);
   57:         y = cimagf(z);
   58:         absa = cabsf (a);
   59:         if (absa == 0.0f) {
   60:                 return (0.0f + 0.0f * I);
   61:         }
   62:         arga = cargf (a);
   63:         r = powf (absa, x);
   64:         theta = x * arga;
   65:         if (y != 0.0f) {
   66:                 r = r * expf (-y * arga);
   67:                 theta = theta + y * logf (absa);
   68:         }
   69:         w = r * cosf (theta) + (r * sinf (theta)) * I;
   70:         return (w);
   71: }