2.9BSD - /usr/src/lib/m/sin.c

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

Defined functions

Defined variables