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LibM: Switch sin() for fast sin()

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faissaloo 2019-06-21 21:42:13 +01:00 • committed by Andreas Kling
parent e38c3bce15
commit 25e8498dcc
1 changed files with 16 additions and 23 deletions
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39
LibM/math.cpp
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@ -12,34 +12,27 @@ double cos(double angle)
return sin(angle + M_PI_2); return sin(angle + M_PI_2);
} }
static double sin_helper(double a) double ampsin(double angle)
{ {
double a3 = a * a * a; double looped_angle = fmod(M_PI + angle, M_TAU) - M_PI;
double a5 = a3 * a * a; double looped_angle_squared = looped_angle * looped_angle;
return a - a3 / 6.0 + a5 / 120.0;
}
static double cos_helper(double a) double quadratic_term;
{ if (looped_angle > 0) {
double a2 = a * a; quadratic_term = -looped_angle_squared;
double a4 = a2 * a2; } else {
return 1 - a2 / 2.0 + a4 / 24.0; quadratic_term = looped_angle_squared;
}
double linear_term = M_PI * looped_angle;
return quadratic_term + linear_term;
} }
double sin(double angle) double sin(double angle)
{ {
double a = fmod(angle, M_TAU); double vertical_scaling = M_PI_2 * M_PI_2;
if (a < 0) return ampsin(angle) / vertical_scaling;
a += M_TAU;
if (a <= M_PI_2 * 0.5)
return sin_helper(a);
if (a <= M_PI_2)
return cos_helper(M_PI_2 - a);
if (a <= M_PI_2 * 1.5)
return cos_helper(a - M_PI_2);
if (a <= M_PI)
return sin_helper(M_PI - a);
return -sin(angle - M_PI);
} }
double pow(double x, double y) double pow(double x, double y)
@ -62,7 +55,7 @@ double tanh(double)
double tan(double angle) double tan(double angle)
{ {
return sin(angle) / cos(angle); return ampsin(angle) / ampsin(M_PI_2 + angle);
} }
double sqrt(double) double sqrt(double)