public static bool operator ==(Quaternion lhs, Quaternion rhs)
{
// Return true if the fields match:
var result =
FloatAlmostEqual (lhs.x, rhs.x) &&
FloatAlmostEqual (lhs.y, rhs.y) &&
FloatAlmostEqual (lhs.z, rhs.z) &&
FloatAlmostEqual (lhs.s, rhs.s);
return result;
}