def __init__(self, mesh, J, name="exchange"):
self.mesh = mesh
# J is a scalar field, because that's good enough for uniform
# exchange. Could be changed trivially by making J a vector field
# and changing the J = self.J[c_i] line in the compute method.
self.J = scalar_field(mesh, J)
# field and energy are just np.arrays. In principle, they could be
# created in the scope of the compute method, but we want to avoid
# re-creating the objects in memory unnecessarily.
self.field = vector_field(mesh, 0)
self.energy = scalar_field(mesh, 0)
self.in_jacobian = True
def test_initialise_scalar():
mesh = CuboidMesh(1, 1, 1, 1, 1, 1)
f = scalar_field(mesh, lambda r: r[0] + r[1] + r[2])
assert np.allclose(f, np.array((1.5)))