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AP_Math: change fast_atan2 to use atan2f on fast CPUs

This commit is contained in:
Jonathan Challinger 2015-02-02 15:02:39 -08:00 committed by Randy Mackay
parent b64077ac2e
commit 5f7480b740
1 changed files with 41 additions and 34 deletions
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75
libraries/AP_Math/AP_Math.cpp
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@ -38,40 +38,47 @@ float fast_atan(float v)
return (v*(1.6867629106f + v2*0.4378497304f)/(1.6867633134f + v2));
}
#define FAST_ATAN2_PIBY2_FLOAT 1.5707963f
// fast_atan2 - faster version of atan2
// 126 us on AVR cpu vs 199 for regular atan2
// absolute error is < 0.005 radians or 0.28 degrees
// origin source: https://gist.github.com/volkansalma/2972237/raw/
float fast_atan2(float y, float x)
{
if (x == 0.0f) {
if (y > 0.0f) {
return FAST_ATAN2_PIBY2_FLOAT;
}
if (y == 0.0f) {
return 0.0f;
}
return -FAST_ATAN2_PIBY2_FLOAT;
}
float atan;
float z = y/x;
if (fabs( z ) < 1.0f) {
atan = z / (1.0f + 0.28f * z * z);
if (x < 0.0f) {
if (y < 0.0f) {
return atan - PI;
}
return atan + PI;
}
} else {
atan = FAST_ATAN2_PIBY2_FLOAT - (z / (z * z + 0.28f));
if (y < 0.0f) {
return atan - PI;
}
}
return atan;
}
#if HAL_CPU_CLASS < HAL_CPU_CLASS_75 || CONFIG_HAL_BOARD == HAL_BOARD_AVR_SITL
#define FAST_ATAN2_PIBY2_FLOAT 1.5707963f
// fast_atan2 - faster version of atan2
// 126 us on AVR cpu vs 199 for regular atan2
// absolute error is < 0.005 radians or 0.28 degrees
// origin source: https://gist.github.com/volkansalma/2972237/raw/
float fast_atan2(float y, float x)
{
if (x == 0.0f) {
if (y > 0.0f) {
return FAST_ATAN2_PIBY2_FLOAT;
}
if (y == 0.0f) {
return 0.0f;
}
return -FAST_ATAN2_PIBY2_FLOAT;
}
float atan;
float z = y/x;
if (fabs( z ) < 1.0f) {
atan = z / (1.0f + 0.28f * z * z);
if (x < 0.0f) {
if (y < 0.0f) {
return atan - PI;
}
return atan + PI;
}
} else {
atan = FAST_ATAN2_PIBY2_FLOAT - (z / (z * z + 0.28f));
if (y < 0.0f) {
return atan - PI;
}
}
return atan;
}
#else
float fast_atan2(float y, float x)
{
return atan2f(y,x);
}
#endif
#if ROTATION_COMBINATION_SUPPORT
// find a rotation that is the combination of two other