kopia lustrzana https://github.com/xaelsouth/rtl-wmbus
78 wiersze
1.5 KiB
C
78 wiersze
1.5 KiB
C
#ifndef ATAN2_H
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#define ATAN2_H
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#include <math.h>
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static inline float atan2_libm(float complex y)
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{
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return cargf(y) * (float)M_1_PI;
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}
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/** https://gist.github.com/volkansalma/2972237 */
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static inline float atan2_approximation(float complex s)
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{
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static const float ONEQTR_PI = M_PI / 4.0;
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static const float THRQTR_PI = 3.0 * M_PI / 4.0;
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float y = cimagf(s), x = crealf(s);
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float r, angle;
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float abs_y = fabs(y) + 1e-10f; // kludge to prevent 0/0 condition
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if (x < 0.0f)
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{
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r = (x + abs_y) / (abs_y - x);
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angle = THRQTR_PI;
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}
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else
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{
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r = (x - abs_y) / (x + abs_y);
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angle = ONEQTR_PI;
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}
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angle += (0.1963f*(float)M_1_PI * r * r - 0.9817f*(float)M_1_PI) * r;
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if (y < 0.0f)
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angle = -angle; // negate if in quad III or IV
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return angle;
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}
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/** https://gist.github.com/volkansalma/2972237 */
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static inline float atan2_approximation2(float complex s)
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{
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float y = cimagf(s), x = crealf(s);
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if (x == 0.0f)
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{
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if (y > 0.0f) return 0.5f;
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if (y == 0.0f) return 0.0f;
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return -0.5f;
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}
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float atan;
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const float z = y / x;
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if (fabs(z) < 1.0f)
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{
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atan = z / (1.0f*(float)M_PI + 0.28086f*(float)M_PI*z*z);
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if (x < 0.0f)
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{
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if (y < 0.0f) return atan - 1.0f;
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return atan + 1.0f;
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}
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}
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else
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{
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atan = 0.5f - z / (z*z + 0.28086f) * (float)M_1_PI;
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if ( y < 0.0f ) return atan - 1.0f;
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}
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return atan;
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}
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#endif /* ATAN2_H */
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