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Try another sine approx. not very good.

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Henrik Rydgard 2013-11-30 20:49:27 +01:00
parent c1b43e1b2d
commit f7bd435375
1 changed files with 35 additions and 1 deletions
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36
unittest/UnitTest.cpp
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@ -78,6 +78,9 @@ float fastasin(double x) {
float sign = x >= 0.0f ? 1.0f : -1.0f;
x = fabs(x);
float sqrtthing = sqrt(1.0f - x * x);
// note that the sqrt can run parallel while we do the rest
// if the hardware supports it
float y = -.3572142480f + .1087063463f * x;
y = y * x + 1.062519236f;
y = y * x + -2.511278506f;
@ -149,10 +152,41 @@ void fcs(float angle, float &sinout, float &cosout) {
cosout = x + temp; // 1 add
}
}
#undef C
const float PI_SQR = 9.86960440108935861883449099987615114f;
//https://code.google.com/p/math-neon/source/browse/trunk/math_floorf.c?r=18
// About 2 correct decimals. Not great.
void fcs2(float theta, float &outsine, float &outcosine) {
float gamma = theta + 1;
gamma += 2;
gamma /= 4;
theta += 2;
theta /= 4;
//theta -= (float)(int)theta;
//gamma -= (float)(int)gamma;
theta -= floorf(theta);
gamma -= floorf(gamma);
theta *= 4;
theta -= 2;
gamma *= 4;
gamma -= 2;
const float B = 2;
float x = 2 * gamma - gamma * abs(gamma);
float y = 2 * theta - theta * abs(theta);
const float P = 0.225;
outsine = P * (y * abs(y) - y) + y; // Q * y + P * y * abs(y)
outcosine = P * (x * abs(x) - x) + x; // Q * y + P * y * abs(y)
}
void fastsincos(float x, float &sine, float &cosine) {
fcs(x, sine, cosine);
fcs2(x, sine, cosine);
}
bool TestSinCos() {