def test_angle_axis():
for M, q in eg_pairs:
theta, vec = nq.quat2angle_axis(q)
q2 = nq.angle_axis2quat(theta, vec)
yield nq.nearly_equivalent, q, q2
aa_mat = nq.angle_axis2mat(theta, vec)
yield assert_array_almost_equal, aa_mat, M
def angle_axis2euler(theta, vector, is_normalized=False):
''' Convert angle, axis pair to Euler angles
Parameters
----------
theta : scalar
angle of rotation
vector : 3 element sequence
vector specifying axis for rotation.
is_normalized : bool, optional
True if vector is already normalized (has norm of 1). Default
False
Returns
-------
z : scalar
y : scalar
x : scalar
Rotations in radians around z, y, x axes, respectively
Examples
--------
>>> z, y, x = angle_axis2euler(0, [1, 0, 0])
>>> np.allclose((z, y, x), 0)
True
Notes
-----
It's possible to reduce the amount of calculation a little, by
combining parts of the ``angle_axis2mat`` and ``mat2euler``
functions, but the reduction in computation is small, and the code
repetition is large.
'''
# delayed import to avoid cyclic dependencies
import nipy.io.imageformats.quaternions as nq
M = nq.angle_axis2mat(theta, vector, is_normalized)
return mat2euler(M)