sysdeps/generic/sincos.c

   1 /*
   2  * Copyright (c) 1987, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by the University of
  16  *      California, Berkeley and its contributors.
  17  * 4. Neither the name of the University nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  */
  33
  34 #ifndef lint
  35 static char sccsid[] = "@(#)sincos.c    8.1 (Berkeley) 6/4/93";
  36 #endif /* not lint */
  37
  38 #include "trig.h"
  39 double
  40 sin(x)
  41 double x;
  42 {
  43         double a,c,z;
  44
  45         if(!finite(x))          /* sin(NaN) and sin(INF) must be NaN */
  46                 return x-x;
  47         x=drem(x,PI2);          /* reduce x into [-PI,PI] */
  48         a=copysign(x,one);
  49         if (a >= PIo4) {
  50                 if(a >= PI3o4)          /* ... in [3PI/4,PI] */
  51                         x = copysign((a = PI-a),x);
  52                 else {                  /* ... in [PI/4,3PI/4]  */
  53                         a = PIo2-a;             /* rtn. sign(x)*C(PI/2-|x|) */
  54                         z = a*a;
  55                         c = cos__C(z);
  56                         z *= half;
  57                         a = (z >= thresh ? half-((z-half)-c) : one-(z-c));
  58                         return copysign(a,x);
  59                 }
  60         }
  61
  62         if (a < small) {                /* rtn. S(x) */
  63                 big+a;
  64                 return x;
  65         }
  66         return x+x*sin__S(x*x);
  67 }
  68
  69 double
  70 cos(x)
  71 double x;
  72 {
  73         double a,c,z,s = 1.0;
  74
  75         if(!finite(x))          /* cos(NaN) and cos(INF) must be NaN */
  76                 return x-x;
  77         x=drem(x,PI2);          /* reduce x into [-PI,PI] */
  78         a=copysign(x,one);
  79         if (a >= PIo4) {
  80                 if (a >= PI3o4) {       /* ... in [3PI/4,PI] */
  81                         a = PI-a;
  82                         s = negone;
  83                 }
  84                 else {                  /* ... in [PI/4,3PI/4] */
  85                         a = PIo2-a;
  86                         return a+a*sin__S(a*a); /* rtn. S(PI/2-|x|) */
  87                 }
  88         }
  89         if (a < small) {
  90                 big+a;
  91                 return s;               /* rtn. s*C(a) */
  92         }
  93         z = a*a;
  94         c = cos__C(z);
  95         z *= half;
  96         a = (z >= thresh ? half-((z-half)-c) : one-(z-c));
  97         return copysign(a,s);
  98 }