Function test_derivative_block

python/test/unit/fem/test_forms.py:148–198

Test the function derivative_block.

()

def test_derivative_block():
    """Test the function derivative_block."""
    mesh = dolfinx.mesh.create_unit_interval(MPI.COMM_WORLD, 10)
    V0 = functionspace(mesh, ("Lagrange", 1))
    V1 = functionspace(mesh, ("Lagrange", 2))
    V = MixedFunctionSpace(V0, V1)

    f0, f1 = dolfinx.fem.Function(V0), dolfinx.fem.Function(V1)
    v0, v1 = TestFunctions(V)
    u0, u1 = TrialFunctions(V)

    M = f0**2 * dx  # univariate functional

    F = derivative_block(M, f0)
    assert isinstance(F, ufl_form) and len(F.arguments()) == 1

    F = derivative_block(M, f0, v0)
    assert isinstance(F, ufl_form) and len(F.arguments()) == 1

    J = derivative_block(F, f0)
    assert isinstance(J, ufl_form) and len(J.arguments()) == 2

    J = derivative_block(F, f0, u0)
    assert isinstance(J, ufl_form) and len(J.arguments()) == 2

    M_block = f0**2 * f1 * dx  # multivariate functional

    F_block = derivative_block(M_block, [f0, f1])
    assert all(isinstance(F_i, ufl_form) and len(F_i.arguments()) == 1 for F_i in F_block)

    F_block = derivative_block(M_block, [f0, f1], [v0, v1])
    assert all(isinstance(F_i, ufl_form) and len(F_i.arguments()) == 1 for F_i in F_block)

    with pytest.raises(ValueError):
        derivative_block(F_block, f0)  # second argument not a sequence

    with pytest.raises(ValueError):
        derivative_block(F_block, [f0, f1], [u0])  # third argument has wrong length

    with pytest.raises(ValueError):
        derivative_block(F_block, [f0, f1], u0)  # third argument not a sequence

    J_block = derivative_block(F_block, [f0, f1])
    assert all(
        isinstance(J_ij, ufl_form) and len(J_ij.arguments()) == 2 for J_i in J_block for J_ij in J_i
    )

    J_block = derivative_block(F_block, [f0, f1], [u0, u1])
    assert all(
        isinstance(J_ij, ufl_form) and len(J_ij.arguments()) == 2 for J_i in J_block for J_ij in J_i
    )