def test_rotate():
    import numpy as np
    from math import sqrt
    from ase import Atoms
    from ase.utils import rotate, irotate

    def test(xyz):
        a = rotate(xyz)
        ixyz = '%sx,%sy,%sz' % irotate(a)
        a2 = rotate(ixyz)
        print(xyz)
        print(ixyz)
        assert abs(a - a2).max() < 1e-10

    test('10z')
    test('155x,43y,190z')
    test('55x,90y,190z')
    test('180x,-90y,45z')
    test('-180y')
    test('40z,50x')

    norm = np.linalg.norm

    for eps in [1.e-6, 1.e-8]:
        struct = Atoms('H2',
                       [[0, 0, 0],
                        [0, sqrt(1 - eps**2), eps]])
        struct.rotate(struct[1].position, 'y')
        assert abs(norm(struct[1].position) - 1) < 1.e-12
