98 lines
1.4 KiB
C
98 lines
1.4 KiB
C
#include <stdio.h>
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#include <math.h>
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#include <assert.h>
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struct cplx
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{
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float r, i;
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};
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cplx cplx_add(cplx a, cplx b)
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{
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cplx c;
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c.r = a.r + b.r;
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c.i = a.i + b.i;
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return c;
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}
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cplx cplx_sub(cplx a, cplx b)
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{
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cplx c;
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c.r = a.r - b.r;
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c.i = a.i - b.i;
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return c;
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}
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cplx cplx_mul(cplx a, cplx b)
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{
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cplx c;
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c.r = a.r * b.r - a.i * b.i;
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c.i = a.i * b.r + a.r * b.i;
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return c;
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}
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float cplx_abs(cplx a)
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{
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return sqrt(a.r * a.r + a.i * a.i);
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}
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cplx cplx_sum(cplx p, const cplx * a, int n)
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{
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cplx s = {0.0, 0.0};
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cplx c = {1.0, 0.0};
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for(int i=0; i<n; i++)
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{
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s = cplx_add(s, cplx_mul(a[i], c));
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c = cplx_mul(c, p);
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}
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return s;
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}
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int main(void)
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{
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cplx sig[100];
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for(int i=0; i<100; i++)
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{
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sig[i].r = cos(i * 1.3);
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sig[i].i = sin(i * 1.3);
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}
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cplx c = {1.0, 0.0};
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float phi = 0.1 * PI;
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cplx t;
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t.r = cos(phi); t.i = sin(phi);
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float p[20], q[20];
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for(int i=0; i<20; i++)
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{
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p[i] = cplx_abs(cplx_sum(c, sig, 100));
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c = cplx_mul(c, t);
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}
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for(int i=0; i<20; i++)
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{
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float sumr = 0.0, sumi = 0.0;
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for(int j=0; j<100; j++)
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{
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float co = cos(i * j * 0.1 * PI), si = sin(i * j * 0.1 * PI);
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sumr += co * sig[j].r - si * sig[j].i;
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sumi += si * sig[j].r + co * sig[j].i;
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}
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q[i] = sqrt(sumr * sumr + sumi * sumi);
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}
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#if 0
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for(int i=0; i<20; i++)
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{
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printf("%d, %f - %f\n", i, p[i], q[i]);
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}
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#endif
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for(int i=0; i<20; i++)
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assert(fabs(p[i] - q[i]) < 1.0);
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return 0;
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}
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