double
squaredAngle(
const MappedColumnVector& inX,
const MappedColumnVector& inY) {
double cosine = dot(inX, inY) / (inX.norm() * inY.norm());
if (cosine > 1)
cosine = 1;
else if (cosine < -1)
cosine = -1;
double angle = std::acos(cosine);
return angle * angle;
}
double
distAngle(
const MappedColumnVector& inX,
const MappedColumnVector& inY) {
// Deal with the undefined case where one of the norm is zero
// Angle is not defined. Just return \pi.
double xnorm = inX.norm(), ynorm = inY.norm();
if (xnorm < std::numeric_limits<double>::denorm_min()
|| ynorm < std::numeric_limits<double>::denorm_min())
return std::acos(-1);
double cosine = dot(inX, inY) / (xnorm * ynorm);
if (cosine > 1)
cosine = 1;
else if (cosine < -1)
cosine = -1;
return std::acos(cosine);
}