[ot][spam][crazy][is it appropriate to direct disruption towards things that have been heavily disrupted?]

[Undiscussed Horrific Abuse, One Victim of Many]

ended up looking like this:

    @classmethod
    def fromaxisangle(cls, axis, angle):
        # from https://en.wikipedia.org/wiki/Rotation_matrix#Rotation_matrix_from_axis_and_angle
        cos_theta = np.cos(angle)
        sin_theta = np.sin(angle)
        axis = axis[:3]
        axis = axis / np.linalg.norm(axis)
        mat = np.identity(4)
        I = mat[:3,:3]
        mat[:3, :3] =  (
            cos_theta * I +
            sin_theta * np.cross(axis, -I) +
            (1 - cos_theta) * np.outer(axis, axis)
        )
        return cls(mat)

$ python3 test.py
[[ 0.98006658  0.          0.19866933  0.        ]
 [ 0.          1.          0.          0.        ]
 [-0.19866933  0.          0.98006658  0.        ]
 [ 0.          0.          0.          1.        ]]

This is a reasonable rotation matrix about the second axis. Since it's
rotating about the second axis, it changes only the first and third,
and the values are perpendicular sines and cosines.