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Annotation of researchv9/libc/math/sin.c, revision 1.1.1.1

1.1       root        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: }

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