102 lines
1.9 KiB
C
102 lines
1.9 KiB
C
/*
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* (c) copyright 1983 by the Vrije Universiteit, Amsterdam, The Netherlands.
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*
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* This product is part of the Amsterdam Compiler Kit.
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*
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* Permission to use, sell, duplicate or disclose this software must be
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* obtained in writing. Requests for such permissions may be sent to
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*
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* Dr. Andrew S. Tanenbaum
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* Wiskundig Seminarium
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* Vrije Universiteit
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* Postbox 7161
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* 1007 MC Amsterdam
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* The Netherlands
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*
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*/
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/* $Header$ */
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/* Author: J.W. Stevenson */
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extern double _fif();
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/*
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C program for floating point sin/cos.
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Calls _fif.
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There are no error exits.
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Coefficients are #3370 from Hart & Cheney (18.80D).
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*/
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static double twoopi = 0.63661977236758134308;
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static double p0 = .1357884097877375669092680e8;
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static double p1 = -.4942908100902844161158627e7;
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static double p2 = .4401030535375266501944918e6;
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static double p3 = -.1384727249982452873054457e5;
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static double p4 = .1459688406665768722226959e3;
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static double q0 = .8644558652922534429915149e7;
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static double q1 = .4081792252343299749395779e6;
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static double q2 = .9463096101538208180571257e4;
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static double q3 = .1326534908786136358911494e3;
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static double
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sinus(arg, quad)
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double arg;
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int quad;
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{
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double e, f;
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double ysq;
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double x,y;
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int k;
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double temp1, temp2;
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x = arg;
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if(x<0) {
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x = -x;
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quad = quad + 2;
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}
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x = x*twoopi; /*underflow?*/
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if(x>32764){
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y = _fif(x, 10.0, &e);
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e = e + quad;
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_fif(0.25, e, &f);
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quad = e - 4*f;
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}else{
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k = x;
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y = x - k;
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quad = (quad + k) & 03;
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}
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if (quad & 01)
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y = 1-y;
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if(quad > 1)
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y = -y;
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ysq = y*y;
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temp1 = ((((p4*ysq+p3)*ysq+p2)*ysq+p1)*ysq+p0)*y;
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temp2 = ((((ysq+q3)*ysq+q2)*ysq+q1)*ysq+q0);
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return(temp1/temp2);
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}
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double
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_cos(arg)
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double arg;
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{
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if(arg<0)
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arg = -arg;
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return(sinus(arg, 1));
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}
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double
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_sin(arg)
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double arg;
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{
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return(sinus(arg, 0));
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}
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/* EXTENSION */
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double
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_tan(arg)
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double arg;
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{
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return( _sin(arg)/_cos(arg));
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}
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