is_rotation_or_reflection

astropy.coordinates.is_rotation_or_reflection(matrix, atol=None)

Check whether a matrix describes rotation or reflection (or both).

Proper and improper rotations (i.e. rotations without and with a reflection) could be distinguished by the sign of the determinant, but this function does not bother with that because both preserve lengths of vectors.

Parameters:

matrixnumpy.ndarray

The check is performed along the last two axes, which must have equal sizes.

atolpython:float, optional

The allowed absolute difference. If None it defaults to 1e-15 or 5 * epsilon of the matrix’s dtype, if floating.

Returns:

np.ndarray, bool

If the matrix has more than two axes, the check is performed on slices along the last two axes – (M, N, N) => (M, ) bool array.