kopia lustrzana https://github.com/xdsopl/robot36
48 wiersze
987 B
C
48 wiersze
987 B
C
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#include <math.h>
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#include "window.h"
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float sinc(float x)
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{
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return 0 == x ? 1.0 : sinf(M_PI * x) / (M_PI * x);
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}
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float hann(float n, float N, float a)
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{
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(void)a;
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return 0.5 * (1.0 - cosf(2.0 * M_PI * n / (N - 1.0)));
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}
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float hamming(float n, float N, float a)
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{
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(void)a;
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return 0.54 - 0.46 * cosf(2.0 * M_PI * n / (N - 1.0));
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}
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float lanczos(float n, float N, float a)
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{
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(void)a;
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return sinc(2.0 * n / (N - 1.0) - 1.0);
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}
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float gauss(float n, float N, float o)
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{
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return expf(- 1.0/2.0 * powf((n - (N - 1.0) / 2.0) / (o * (N - 1.0) / 2.0), 2.0));
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}
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float i0f(float x)
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{
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// converges for -3*M_PI:3*M_PI in less than 20 iterations
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float sum = 1.0, val = 1.0, c = 0.0;
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for (int n = 1; n < 20; n++) {
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float tmp = x / (2 * n);
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val *= tmp * tmp;
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float y = val - c;
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float t = sum + y;
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c = (t - sum) - y;
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sum = t;
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}
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return sum;
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}
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float kaiser(float n, float N, float a)
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{
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return i0f(M_PI * a * sqrtf(1.0 - powf((2.0 * n) / (N - 1.0) - 1.0, 2.0))) / i0f(M_PI * a);
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}
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