def test_energy_ferro():
''' Check the energy of the ferromagnetic state.'''
size = 4
coupling = 1.0
lattice = Lattice(size, size)
ham = Hamiltonian(lattice, coupling)
assert ham.energy(
ones((size, size), dtype=bool)
) == 2 * coupling * size * size, "Energy of ferromagnetic state is incorrect."
def test_energy_antiferro():
''' Check the energy of the antiferromagnetic state.'''
size = 10
coupling = 1.0
lattice = Lattice(size, size)
ham = Hamiltonian(lattice, coupling)
afm = tile(eye(2, dtype=bool), (5, 5))
assert ham.energy(
afm
) == -2 * coupling * size * size, "Energy of antiferromagnetic state is incorrect."