ardupilot/libraries/AP_Math/AP_Math.cpp

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#include "AP_Math.h"
#include <float.h>
// a varient of asin() that checks the input ranges and ensures a
// valid angle as output. If nan is given as input then zero is
// returned.
float safe_asin(float v)
{
if (isnan(v)) {
return 0.0f;
}
if (v >= 1.0f) {
return PI/2;
}
if (v <= -1.0f) {
return -PI/2;
}
return asinf(v);
}
// a varient of sqrt() that checks the input ranges and ensures a
// valid value as output. If a negative number is given then 0 is
// returned. The reasoning is that a negative number for sqrt() in our
// code is usually caused by small numerical rounding errors, so the
// real input should have been zero
float safe_sqrt(float v)
{
float ret = sqrtf(v);
if (isnan(ret)) {
return 0;
}
return ret;
}
#if ROTATION_COMBINATION_SUPPORT
// find a rotation that is the combination of two other
// rotations. This is used to allow us to add an overall board
// rotation to an existing rotation of a sensor such as the compass
// Note that this relies the set of rotations being complete. The
// optional 'found' parameter is for the test suite to ensure that it is.
enum Rotation rotation_combination(enum Rotation r1, enum Rotation r2, bool *found)
{
Vector3f tv1, tv2;
enum Rotation r;
tv1(1,2,3);
tv1.rotate(r1);
tv1.rotate(r2);
for (r=ROTATION_NONE; r<ROTATION_MAX;
r = (enum Rotation)((uint8_t)r+1)) {
Vector3f diff;
tv2(1,2,3);
tv2.rotate(r);
diff = tv1 - tv2;
if (diff.length() < 1.0e-6f) {
// we found a match
if (found) {
*found = true;
}
return r;
}
}
// we found no matching rotation. Someone has edited the
// rotations list and broken its completeness property ...
if (found) {
*found = false;
}
return ROTATION_NONE;
}
#endif