update: format
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c8874275c3
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ad173aa8ae
49
sin.c
49
sin.c
@ -59,7 +59,8 @@ static double atanlist[100] = {
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3.1554436208840472216469142611311e-30, 1.5777218104420236108234571305656e-30
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};
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int trig(double theta, double *xy, double *dxy){
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int trig(double theta, double *xy, double *dxy)
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{
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int i = 0;
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double t = 1.0; // t=2^-i
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int d = 0;
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@ -68,7 +69,8 @@ int trig(double theta, double *xy, double *dxy){
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xy[0] = x0;
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xy[1] = y0;
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while(i<100 && dnorm>1e-32){
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while (i < 100 && dnorm > 1e-32)
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{
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d = alpha > 0 ? 1 : (alpha < 0 ? -1 : 0);
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dxy[0] = -d * xy[1] * t;
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dxy[1] = d * xy[0] * t;
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@ -82,11 +84,16 @@ int trig(double theta, double *xy, double *dxy){
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return i;
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}
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double sin1(double theta, int *it, double *dsin){
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if(theta < 0) return -sin1(theta, it, dsin);
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if(theta > 2*PI) return sin1(theta - 2*PI, it, dsin);
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if(theta > PI) return -sin1(theta - PI, it, dsin);
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if(theta > PI/2) return sin1(PI - theta, it, dsin);
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double sin1(double theta, int *it, double *dsin)
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{
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if (theta < 0)
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return -sin1(theta, it, dsin);
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if (theta > 2 * PI)
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return sin1(theta - 2 * PI, it, dsin);
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if (theta > PI)
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return -sin1(theta - PI, it, dsin);
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if (theta > PI / 2)
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return sin1(PI - theta, it, dsin);
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double xy[2];
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double dxy[2];
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@ -96,16 +103,22 @@ double sin1(double theta, int *it, double *dsin){
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return xy[1];
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}
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double sin2(double theta, int *it, double *dsin){
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if(theta < 0) return -sin2(theta, it, dsin);
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if(theta > 2*PI) return sin2(theta - 2*PI, it, dsin);
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if(theta > PI) return -sin2(theta - PI, it, dsin);
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if(theta > PI/2) return sin2(PI - theta, it, dsin);
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double sin2(double theta, int *it, double *dsin)
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{
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if (theta < 0)
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return -sin2(theta, it, dsin);
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if (theta > 2 * PI)
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return sin2(theta - 2 * PI, it, dsin);
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if (theta > PI)
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return -sin2(theta - PI, it, dsin);
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if (theta > PI / 2)
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return sin2(PI - theta, it, dsin);
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double result = 0;
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double term = theta;
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int i = 0;
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while (i<100 && fabs(term)>1e-16){
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while (i < 100 && fabs(term) > 1e-16)
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{
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result += term;
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i += 1;
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term *= -1;
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@ -118,20 +131,24 @@ double sin2(double theta, int *it, double *dsin){
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return result;
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}
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int main(){
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int main()
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{
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int it;
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double theta = 1.0;
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double sin, dsin;
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clock_t start, end;
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start = clock();
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for (int i=0; i<10000; i++) sin = sin1(theta, &it, &dsin);
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for (int i = 0; i < 10000; i++)
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sin = sin1(theta, &it, &dsin);
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end = clock();
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printf("sin1(%.16g) = %.16g, it = %d, dsin=%.16g, took %.16g s.\n", theta, sin, it, dsin, (double)(end - start) / CLOCKS_PER_SEC);
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start = clock();
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for (int i=0; i<10000; i++) sin = sin2(theta, &it, &dsin);
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for (int i = 0; i < 10000; i++)
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sin = sin2(theta, &it, &dsin);
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end = clock();
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printf("sin2(%.16g) = %.16g, it = %d, dsin=%.16g, took %.16g s.\n", theta, sin, it, dsin, (double)(end - start) / CLOCKS_PER_SEC);
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return 0;
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}
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