4.3BSD - /usr/src/usr.lib/libom/sin.c

   1: /*	@(#)sin.c	4.1	12/25/82	*/
   2: 
   3: /*
   4: 	C program for floating point sin/cos.
   5: 	Calls modf.
   6: 	There are no error exits.
   7: 	Coefficients are #3370 from Hart & Cheney (18.80D).
   8: */
   9: 
  10: static double twoopi    = 0.63661977236758134308;
  11: static double p0    =  .1357884097877375669092680e8;
  12: static double p1    = -.4942908100902844161158627e7;
  13: static double p2    =  .4401030535375266501944918e6;
  14: static double p3    = -.1384727249982452873054457e5;
  15: static double p4    =  .1459688406665768722226959e3;
  16: static double q0    =  .8644558652922534429915149e7;
  17: static double q1    =  .4081792252343299749395779e6;
  18: static double q2    =  .9463096101538208180571257e4;
  19: static double q3    =  .1326534908786136358911494e3;
  20: 
  21: double
  22: cos(arg)
  23: double arg;
  24: {
  25:     double sinus();
  26:     if(arg<0)
  27:         arg = -arg;
  28:     return(sinus(arg, 1));
  29: }
  30: 
  31: double
  32: sin(arg)
  33: double arg;
  34: {
  35:     double sinus();
  36:     return(sinus(arg, 0));
  37: }
  38: 
  39: static double
  40: sinus(arg, quad)
  41: double arg;
  42: int quad;
  43: {
  44:     double modf();
  45:     double e, f;
  46:     double ysq;
  47:     double x,y;
  48:     int k;
  49:     double temp1, temp2;
  50: 
  51:     x = arg;
  52:     if(x<0) {
  53:         x = -x;
  54:         quad = quad + 2;
  55:     }
  56:     x = x*twoopi;   /*underflow?*/
  57:     if(x>32764){
  58:         y = modf(x,&e);
  59:         e = e + quad;
  60:         modf(0.25*e,&f);
  61:         quad = e - 4*f;
  62:     }else{
  63:         k = x;
  64:         y = x - k;
  65:         quad = (quad + k) & 03;
  66:     }
  67:     if (quad & 01)
  68:         y = 1-y;
  69:     if(quad > 1)
  70:         y = -y;
  71: 
  72:     ysq = y*y;
  73:     temp1 = ((((p4*ysq+p3)*ysq+p2)*ysq+p1)*ysq+p0)*y;
  74:     temp2 = ((((ysq+q3)*ysq+q2)*ysq+q1)*ysq+q0);
  75:     return(temp1/temp2);
  76: }

Defined functions

Defined variables