def test_distance():
    import itertools
    import numpy as np

    from ase import Atoms, Atom
    from ase.geometry import distance

    # artificial structure
    org = Atoms('COPNS',
                [[-1.75072, 0.62689, 0.00000],
                 [0.58357, 2.71652, 0.00000],
                 [-5.18268, 1.36522, 0.00000],
                 [-1.86663, -0.77867, 2.18917],
                 [-1.80586, 0.20783, -2.79331]])

    maxdist = 3.0e-13

    # translate
    for dx in range(3, 10, 2):
        new = org.copy()
        new.translate([dx / np.sqrt(2), -dx / np.sqrt(2), 0])
        dist = distance(org, new, True)
        dist2 = distance(org, new, False)
        print('translation', dx, '-> distance', dist)
        assert dist < maxdist
        assert dist == dist2

    # rotate
    for axis in ['x', '-y', 'z', np.array([1, 1, 1] / np.sqrt(3))]:
        for rot in [20, 200]:
            new = org.copy()
            new.translate(-new.get_center_of_mass())
            new.rotate(rot, axis)
            dist = distance(org, new, True)
            dist2 = distance(org, new, False)
            print('rotation', axis, ', angle', rot, '-> distance', dist)
            assert dist < maxdist
            assert dist == dist2

    if 0:
        # reflect
        new = Atoms()
        cm = org.get_center_of_mass()
        for a in org:
            new.append(Atom(a.symbol, -(a.position - cm)))
        dist = distance(org, new)
        print('reflected -> distance', dist)

    # permute
    for i, a in enumerate(org):
        if i < 3:
            a.symbol = 'H'

    for indxs in itertools.permutations(range(3)):
        new = org.copy()
        for c in range(3):
            new[c].position = org[indxs[c]].position
        dist = distance(org, new)
        print('permutation', indxs, '-> distance', dist)
        assert dist < maxdist
