def convert_rotor(self, theta=None, phi=None, pivot=None, com=None):
"""Convert the rotor axis spherical angles to the axis alpha notation.
The pivot will be shifted to the point on the axis closest to the CoM, and the alpha angle set.
@keyword theta: The polar spherical angle.
@type theta: float
@keyword phi: The azimuthal spherical angle.
@type phi: float
@keyword pivot: The pivot point on the rotation axis.
@type pivot: numpy rank-1 3D array
@keyword com: The pivot point on the rotation axis.
@type com: numpy rank-1 3D array
"""
# The axis.
axis = zeros(3, float64)
spherical_to_cartesian([1.0, theta, phi], axis)
# Reset the pivot to the closest point on the line to the CoM (shift the pivot).
self.PIVOT = closest_point_ax(line_pt=pivot, axis=axis, point=com)
# The CoM-pivot unit vector (for the shifted pivot).
piv_com = com - self.PIVOT
piv_com = piv_com / norm(piv_com)
# The vector perpendicular to the CoM-pivot vector.
z_axis = array([0, 0, 1], float64)
perp_vect = cross(piv_com, z_axis)
perp_vect = perp_vect / norm(perp_vect)
# Set the alpha angle (the angle between the perpendicular vector and the axis).
self.AXIS_ALPHA = vector_angle_normal(perp_vect, axis, piv_com)
def convert_rotor(self, theta=None, phi=None, pivot=None, com=None):
"""Convert the rotor axis spherical angles to the axis alpha notation.
The pivot will be shifted to the point on the axis closest to the CoM, and the alpha angle set.
@keyword theta: The polar spherical angle.
@type theta: float
@keyword phi: The azimuthal spherical angle.
@type phi: float
@keyword pivot: The pivot point on the rotation axis.
@type pivot: numpy rank-1 3D array
@keyword com: The pivot point on the rotation axis.
@type com: numpy rank-1 3D array
"""
# The axis.
axis = zeros(3, float64)
spherical_to_cartesian([1.0, theta, phi], axis)
# Reset the pivot to the closest point on the line to the CoM (shift the pivot).
self.PIVOT = closest_point_ax(line_pt=pivot, axis=axis, point=com)
# The CoM-pivot unit vector (for the shifted pivot).
piv_com = com - self.PIVOT
piv_com = piv_com / norm(piv_com)
# The vector perpendicular to the CoM-pivot vector.
z_axis = array([0, 0, 1], float64)
perp_vect = cross(piv_com, z_axis)
perp_vect = perp_vect / norm(perp_vect)
# Set the alpha angle (the angle between the perpendicular vector and the axis).
self.AXIS_ALPHA = vector_angle_normal(perp_vect, axis, piv_com)
def test_vector_angle_normal6(self):
"""Test the vector_angle_normal() function with the vectors [2, 2, 0] and [2, -2, 0]."""
# Calculate the angle.
v1 = array([2, 2, 0], float64)
v2 = array([2, -2, 0], float64)
normal = array([0, 0, 2], float64)
angle = vector_angle_normal(v1, v2, normal)
# Check the angle.
self.assertAlmostEqual(angle, -pi/2.0)
