Add method to find angle between 2 vectors. about pyansys-geometry HOT 3 CLOSED

self._center, self._start, self._end = center, start, end
self._axis = axis

to_start_vector = QuantityVector.from_points(self._start, self._center)
self._radius = to_start_vector.norm

if not self._radius.m > 0:
    raise ValueError("Point configuration does not yield a positive length arc radius.")

direction_x = UnitVector(to_start_vector.normalize())
direction_y = UnitVector((axis % direction_x).normalize())
to_end_vector = UnitVector.from_points(self._end, self._center)
self._angle = np.arctan2(direction_y * to_end_vector, direction_x * to_end_vector)
if self._angle < 0:
    self._angle = (2 * np.pi) + self._angle