def test_separate_by_order():
u, v = Variables('u v')
c, f = Constants('c f')
strong_form = StrongForm(c*grad(div(u)) + div(v) - f + dot(c, grad(u)))
order_dict = strong_form.separate_by_order()
assert(order_dict[0] == -f)
assert(order_dict[1] == div(v) + dot(c, grad(u)))
assert(order_dict[2] == c*grad(div(u)))
def test_extract_transport_coefficients():
u = Variable('u', rank=0)
a, b, d = Coefficients('a b d', rank=0)
b, e = Coefficients('b e', rank=1)
c, = Coefficients('c', rank=2)
eqn = Dt(a*u) + div(b*u + c*grad(u)) + d*u + dot(e, grad(u))
strong_form = StrongForm(eqn)
coeffs = {'diffusion': c,
'reaction': d*u,
'hamiltonian': dot(e, grad(u)),
'potential': u,
'mass': Dt(a*u),
'advection': b*u,
}
sf_coeffs = strong_form.extract_transport_coefficients()
assert(coeffs == sf_coeffs)
eqn = d*u + dot(e, grad(u)) + Dt(a*u) + div(b*u) + div(c*grad(u))
strong_form = StrongForm(eqn)
sf_coeffs = strong_form.extract_transport_coefficients()
assert(coeffs == sf_coeffs)