contrib/openbsd_libm/src/s_cacosl.c

   1 /*      $OpenBSD: s_cacosl.c,v 1.3 2011/07/20 21:02:51 martynas Exp $   */
   2
   3 /*
   4  * Copyright (c) 2008 Stephen L. Moshier <steve@moshier.net>
   5  *
   6  * Permission to use, copy, modify, and distribute this software for any
   7  * purpose with or without fee is hereby granted, provided that the above
   8  * copyright notice and this permission notice appear in all copies.
   9  *
  10  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  11  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  12  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  13  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  14  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  15  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  16  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  17  */
  18
  19 /*                                                      cacosl()
  20  *
  21  *      Complex circular arc cosine
  22  *
  23  *
  24  *
  25  * SYNOPSIS:
  26  *
  27  * long double complex cacosl();
  28  * long double complex z, w;
  29  *
  30  * w = cacosl( z );
  31  *
  32  *
  33  *
  34  * DESCRIPTION:
  35  *
  36  *
  37  * w = arccos z  =  PI/2 - arcsin z.
  38  *
  39  *
  40  *
  41  *
  42  * ACCURACY:
  43  *
  44  *                      Relative error:
  45  * arithmetic   domain     # trials      peak         rms
  46  *    DEC       -10,+10      5200      1.6e-15      2.8e-16
  47  *    IEEE      -10,+10     30000      1.8e-14      2.2e-15
  48  */
  49
  50 #include <complex.h>
  51 #include <math.h>
  52
  53 static const long double PIO2L = 1.570796326794896619231321691639751442098585L;
  54
  55 long double complex
  56 cacosl(long double complex z)
  57 {
  58         long double complex w;
  59
  60         w = casinl(z);
  61         w = (PIO2L - creall(w)) - cimagl(w) * I;
  62         return (w);
  63 }