Пример #1
0
def test_terminal_expr_bilinear_2d_2():

    domain = Domain('Omega', dim=2)
    B1 = Boundary(r'\Gamma_1', domain)

    x, y = domain.coordinates

    kappa = Constant('kappa', is_real=True)
    mu = Constant('mu', is_real=True)
    nn = NormalVector('nn')

    V = VectorFunctionSpace('V', domain)

    u, u1, u2 = [element_of(V, name=i) for i in ['u', 'u1', 'u2']]
    v, v1, v2 = [element_of(V, name=i) for i in ['v', 'v1', 'v2']]

    # ...
    int_0 = lambda expr: integral(domain, expr)
    int_1 = lambda expr: integral(B1, expr)

    a = BilinearForm((u, v), int_0(dot(u, v)))
    print(TerminalExpr(a))
    print('')

    # ...
    a = BilinearForm((u, v), int_0(inner(grad(u), grad(v))))
    print(TerminalExpr(a))
    print('')
    # ...

    # ...
    a = BilinearForm((u, v), int_0(dot(u, v) + inner(grad(u), grad(v))))
    print(TerminalExpr(a))
    print('')
Пример #2
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def test_latex_2d_2():

    DIM = 2
    domain = Domain('Omega', dim=DIM)

    V = VectorFunctionSpace('V', domain)

    x, y = V.coordinates

    v = element_of(V, name='v')
    u = element_of(V, name='u')
    #    F = element_of(V, name='F')

    int_0 = lambda expr: integral(domain, expr)

    assert (latex(v) == r'\mathbf{v}')
    assert (latex(inner(
        grad(v), grad(u))) == r'\nabla{\mathbf{u}} : \nabla{\mathbf{v}}')

    a = BilinearForm((v, u), int_0(inner(grad(v), grad(u))))
    print(latex(a))
    #    assert(latex(a) == r'\int_{0}^{1}\int_{0}^{1} \nabla{\mathbf{v}} : \nabla{\mathbf{u}} dxdy')

    b = LinearForm(v, int_0(sin(pi * x) * cos(pi * y) * div(v)))
    print(latex(b))
Пример #3
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def test_calculus_3d_4():
    domain = Domain('Omega', dim=3)

    W = VectorFunctionSpace('W', domain)

    alpha, beta, gamma = [Constant(i) for i in ['alpha', 'beta', 'gamma']]

    F, G, H = elements_of(W, names='F, G, H')

    # ...
    expected = alpha * inner(D(F), D(G)) + beta * inner(D(F), D(H))
    assert (inner(D(F), D(alpha * G + beta * H)) == expected)
Пример #4
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def test_bilinear_form_2d_2():

    domain = Domain('Omega', dim=2)
    B1 = Boundary(r'\Gamma_1', domain)

    x, y = domain.coordinates

    kappa = Constant('kappa', is_real=True)
    mu = Constant('mu', is_real=True)

    V = VectorFunctionSpace('V', domain)

    u, u1, u2 = [element_of(V, name=i) for i in ['u', 'u1', 'u2']]
    v, v1, v2 = [element_of(V, name=i) for i in ['v', 'v1', 'v2']]

    # ...
    int_0 = lambda expr: integral(domain, expr)
    int_1 = lambda expr: integral(B1, expr)

    a = BilinearForm((u, v), int_0(dot(u, v)))

    assert (a.domain == domain.interior)
    assert (a(u1, v1) == int_0(dot(u1, v1)))
    # ...

    # ...
    a = BilinearForm((u, v), int_0(dot(u, v) + inner(grad(u), grad(v))))

    assert (a.domain == domain.interior)
    assert (a(u1, v1) == int_0(dot(u1, v1)) + int_0(inner(grad(u1), grad(v1))))
    # ...

    # ...
    a1 = BilinearForm((u1, v1), int_0(dot(u1, v1)))
    a = BilinearForm((u, v), a1(u, v))

    assert (a.domain == domain.interior)
    assert (a(u2, v2) == int_0(dot(u2, v2)))
    # ...

    # ...
    a1 = BilinearForm((u1, v1), int_0(dot(u1, v1)))
    a2 = BilinearForm((u2, v2), int_0(inner(grad(u2), grad(v2))))
    a = BilinearForm((u, v), a1(u, v) + kappa * a2(u, v))

    assert (a.domain == domain.interior)
    assert (a(u,
              v) == int_0(dot(u, v)) + int_0(kappa * inner(grad(u), grad(v))))
Пример #5
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def test_bilinear_form_2d_4():

    domain = Domain('Omega', dim=2)
    B1 = Boundary(r'\Gamma_1', domain)

    x, y = domain.coordinates

    kappa = Constant('kappa', is_real=True)
    mu = Constant('mu', is_real=True)

    V = VectorFunctionSpace('V', domain)

    u, u1, u2 = [element_of(V, name=i) for i in ['u', 'u1', 'u2']]
    v, v1, v2 = [element_of(V, name=i) for i in ['v', 'v1', 'v2']]

    int_0 = lambda expr: integral(domain, expr)
    int_1 = lambda expr: integral(B1, expr)
    # ...
    a = BilinearForm((u, v), int_0(dot(u, v)))
    assert (a.is_symmetric)
    # ...

    # ...
    a = BilinearForm((u, v), int_0(inner(grad(u), grad(v))))
    assert (a.is_symmetric)
Пример #6
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def test_bilinear_expr_2d_2():

    domain = Domain('Omega', dim=2)
    x,y = domain.coordinates

    kappa = Constant('kappa', is_real=True)
    mu    = Constant('mu'   , is_real=True)

    V = VectorFunctionSpace('V', domain)

    u,u1,u2 = [element_of(V, name=i) for i in ['u', 'u1', 'u2']]
    v,v1,v2 = [element_of(V, name=i) for i in ['v', 'v1', 'v2']]

    # ...
    a = BilinearExpr((u,v), dot(u,v))
    print(a)
    print(a.expr)
    print(a(u1,v1))
    # TODO
#    print(a(u1+u2,v1+v2))
    print('')
    # ...

    # ...
    a1 = BilinearExpr((u,v), dot(u,v))
    a2 = BilinearExpr((u,v), inner(grad(u),grad(v)))
    print(a1(u1,v1) + a2(u2,v2))
    print('')
Пример #7
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def test_equation_2d_4():

    V = VectorFunctionSpace('V', domain)

    v = element_of(V, name='v')
    u = element_of(V, name='u')
    x, y = domain.coordinates

    B1 = Boundary(r'\Gamma_1', domain)

    int_0 = lambda expr: integral(domain, expr)
    int_1 = lambda expr: integral(B1, expr)

    # ... bilinear/linear forms
    a1 = BilinearForm((v, u), int_0(inner(grad(v), grad(u))))

    f = Tuple(x * y, sin(pi * x) * sin(pi * y))
    l1 = LinearForm(v, int_0(dot(f, v)))
    # ...

    # ...
    bc = EssentialBC(u, 0, B1)
    eq = Equation(a1, l1, tests=v, trials=u, bc=bc)
    # ...

    # ...
    bc = EssentialBC(u[0], 0, B1)
    eq = Equation(a1, l1, tests=v, trials=u, bc=bc)
    # ...

    # ...
    nn = NormalVector('nn')
    bc = EssentialBC(dot(u, nn), 0, B1)
    eq = Equation(a1, l1, tests=v, trials=u, bc=bc)
Пример #8
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def test_compiler_3d_stokes():

    domain = Domain('Omega', dim=3)

    # ...
    #    by setting the space type, we cannot evaluate grad of Hdiv function, then
    #    ArgumentTypeError will be raised.
    #    In order to avoid this problem, we need first to declare our space as an
    #    undefined type.
    Hdiv = VectorFunctionSpace('V2', domain, kind='Hdiv')
    L2 = ScalarFunctionSpace('V3', domain, kind='L2')

    X = Hdiv * L2

    u, p = element_of(X, name='u, p')
    v, q = element_of(X, name='v, q')

    with pytest.raises(ArgumentTypeError):
        expr = inner(grad(u), grad(v)) - div(v) * p + q * div(u)
    # ...

    # ...
    Hdiv = VectorFunctionSpace('V2', domain)
    L2 = ScalarFunctionSpace('V3', domain)

    X = Hdiv * L2

    u, p = element_of(X, name='u, p')
    v, q = element_of(X, name='v, q')

    expr = inner(grad(u), grad(v)) - div(v) * p + q * div(u)
    atoms = {
        u: DifferentialForm('u', index=2, dim=domain.dim),
        v: DifferentialForm('v', index=2, dim=domain.dim),
        p: DifferentialForm('p', index=3, dim=domain.dim),
        q: DifferentialForm('q', index=3, dim=domain.dim)
    }
    newexpr = ExteriorCalculusExpr(expr, tests=[v, q], atoms=atoms)
    print('===== BEFORE =====')
    print(newexpr)

    newexpr = augmented_expression(newexpr,
                                   tests=[v, q],
                                   atoms=atoms,
                                   weak=False)
    print('===== AFTER  =====')
    print(newexpr)
Пример #9
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def test_evaluation_2d_1():
    domain = Domain('Omega', dim=2)
    B_neumann = Boundary(r'\Gamma_1', domain)

    V = FunctionSpace('V', domain)
    W = VectorFunctionSpace('W', domain)

    p, q = [TestFunction(V, name=i) for i in ['p', 'q']]
    u, v = [VectorTestFunction(W, name=i) for i in ['u', 'v']]

    alpha = Constant('alpha')

    x, y = V.coordinates
    F = Field('F', space=V)

    a1 = BilinearForm((p, q), dot(grad(p), grad(q)))
    m = BilinearForm((p, q), p * q)
    a2 = BilinearForm((p, q), a1(p, q) + alpha * m(p, q))
    a3 = BilinearForm((u, v), rot(u) * rot(v) + alpha * div(u) * div(v))

    a11 = BilinearForm((v, u), inner(grad(v), grad(u)))
    a12 = BilinearForm((v, p), div(v) * p)
    a4 = BilinearForm(((v, q), (u, p)), a11(v, u) - a12(v, p) + a12(u, q))

    l0 = LinearForm(p, F * p)
    l_neu = LinearForm(p, p * trace_1(grad(F), B_neumann))
    l = LinearForm(p, l0(p) + l_neu(p))

    # ...
    print(a1)
    print(evaluate(a1))
    print('')
    # ...

    # ...
    print(a2)
    print(evaluate(a2))
    print('')
    # ...

    # ...
    print(a3)
    print(evaluate(a3))
    print('')
    # ...

    # ...
    print(a4)
    print(evaluate(a4))
    print('')
    # ...

    # ...
    print(l)
    print(evaluate(l))
    print('')
Пример #10
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def test_field_2d_1():
    print('============ test_field_2d_1 =============')

    #    x, y = domain.coordinates

    W = VectorFunctionSpace('W', domain)
    F = element_of(W, 'F')

    assert (dx(F) == Matrix([[dx(F[0]), dx(F[1])]]))

    # TODO not working yet => check it for VectorFunction also
    #    print(dx(x*F))

    expr = inner(grad(F), grad(F))
    print(expr)
Пример #11
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def test_equation_2d_5():
    domain = Square()
    x, y = domain.coordinates

    f0 = Matrix([
        2 * pi**2 * sin(pi * x) * sin(pi * y),
        2 * pi**2 * sin(pi * x) * sin(pi * y)
    ])

    f1 = cos(pi * x) * cos(pi * y)

    W = VectorFunctionSpace('W', domain)
    V = ScalarFunctionSpace('V', domain)
    X = ProductSpace(W, V)

    F = element_of(W, name='F')
    G = element_of(V, name='G')

    u, v = [element_of(W, name=i) for i in ['u', 'v']]
    p, q = [element_of(V, name=i) for i in ['p', 'q']]

    int_0 = lambda expr: integral(domain, expr)

    a0 = BilinearForm((v, u), int_0(inner(grad(v), grad(u))))
    print('     a0 done.')
    a1 = BilinearForm((q, p), int_0(p * q))
    print('     a1 done.')
    a = BilinearForm(((v, q), (u, p)), a0(v, u) + a1(q, p))
    print('     a  done.')

    l0 = LinearForm(v, int_0(dot(f0, v)))
    l1 = LinearForm(q, int_0(f1 * q))
    l = LinearForm((v, q), l0(v) + l1(q))

    print('****************************')
    bc = EssentialBC(u, 0, domain.boundary)
    equation = Equation(a, l, tests=[v, q], trials=[u, p], bc=bc)

    # ...
    print('=======')
    print(equation.lhs.expr)
    print('')
    # ...

    # ...
    print('=======')
    print(equation.rhs.expr)
    print('')
Пример #12
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def test_bilinear_form_2d_3():

    domain = Domain('Omega', dim=2)

    x, y = domain.coordinates

    V = VectorFunctionSpace('V', domain)
    W = FunctionSpace('W', domain)

    v = VectorTestFunction(V, name='v')
    u = VectorTestFunction(V, name='u')
    p = TestFunction(W, name='p')
    q = TestFunction(W, name='q')

    a = BilinearForm((u, v), inner(grad(v), grad(u)))
    b = BilinearForm((v, p), div(v) * p)
    A = BilinearForm(((u, p), (v, q)), a(v, u) - b(v, p) + b(u, q))

    export(A, 'stokes_2d.png')
Пример #13
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def test_tensorize_2d_stokes():
    domain = Domain('Omega', dim=DIM)

    # ... abstract model
    V = VectorFunctionSpace('V', domain)
    W = FunctionSpace('W', domain)

    v = VectorTestFunction(V, name='v')
    u = VectorTestFunction(V, name='u')
    p = TestFunction(W, name='p')
    q = TestFunction(W, name='q')

    a = BilinearForm((v, u), inner(grad(v), grad(u)), name='a')
    b = BilinearForm((v, p), div(v) * p, name='b')
    A = BilinearForm(((v, q), (u, p)), a(v, u) - b(v, p) + b(u, q), name='A')
    # ...

    print(A)
    print(tensorize(A))
    print('')
Пример #14
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def test_evaluation_2d_2():
    domain = Square()
    x, y = domain.coordinates

    f0 = Tuple(2 * pi**2 * sin(pi * x) * sin(pi * y),
               2 * pi**2 * sin(pi * x) * sin(pi * y))

    f1 = cos(pi * x) * cos(pi * y)

    W = VectorFunctionSpace('W', domain)
    V = FunctionSpace('V', domain)
    X = ProductSpace(W, V)

    # TODO improve: naming are not given the same way
    F = VectorField(W, name='F')
    G = Field('G', V)

    u, v = [VectorTestFunction(W, name=i) for i in ['u', 'v']]
    p, q = [TestFunction(V, name=i) for i in ['p', 'q']]

    a0 = BilinearForm((v, u), inner(grad(v), grad(u)))
    a1 = BilinearForm((q, p), p * q)
    a = BilinearForm(((v, q), (u, p)), a0(v, u) + a1(q, p))

    l0 = LinearForm(v, dot(f0, v))
    l1 = LinearForm(q, f1 * q)
    l = LinearForm((v, q), l0(v) + l1(q))

    # ...
    print(a)
    print(evaluate(a))
    print('')
    # ...

    # ...
    print(l)
    print(evaluate(l))
    print('')
Пример #15
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def test_terminal_expr_bilinear_2d_4():

    domain = Domain('Omega', dim=2)

    x, y = domain.coordinates

    V = VectorFunctionSpace('V', domain)
    W = ScalarFunctionSpace('W', domain)

    v = element_of(V, name='v')
    u = element_of(V, name='u')
    p = element_of(W, name='p')
    q = element_of(W, name='q')

    int_0 = lambda expr: integral(domain, expr)

    # stokes
    a = BilinearForm((u, v), int_0(inner(grad(v), grad(u))))
    b = BilinearForm((v, p), int_0(div(v) * p))
    a = BilinearForm(((u, p), (v, q)), a(v, u) - b(v, p) + b(u, q))

    print(TerminalExpr(a))
    print('')
Пример #16
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def test_latex_2d_4():
    DIM = 2

    domain = Domain('Omega', dim=DIM)

    # ... abstract model
    V = VectorFunctionSpace('V', domain)
    W = ScalarFunctionSpace('W', domain)

    v = element_of(V, name='v')
    u = element_of(V, name='u')
    p = element_of(W, name='p')
    q = element_of(W, name='q')

    int_0 = lambda expr: integral(domain, expr)

    a = BilinearForm((v, u), int_0(inner(grad(v), grad(u))))
    b = BilinearForm((v, p), int_0(div(v) * p))
    A = BilinearForm(((v, q), (u, p)), a(v, u) - b(v, p) + b(u, q))
    # ...

    print(latex(A))
    #    print(latex(tensorize(A)))
    print('')
Пример #17
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def test_bilinearity_2d_2():
    domain = Domain('Omega', dim=DIM)

    V1 = FunctionSpace('V1', domain)
    V2 = FunctionSpace('V2', domain)
    U1 = FunctionSpace('U1', domain)
    U2 = FunctionSpace('U2', domain)
    W1 = VectorFunctionSpace('W1', domain)
    W2 = VectorFunctionSpace('W2', domain)
    T1 = VectorFunctionSpace('T1', domain)
    T2 = VectorFunctionSpace('T2', domain)

    v1 = TestFunction(V1, name='v1')
    v2 = TestFunction(V2, name='v2')
    u1 = TestFunction(U1, name='u1')
    u2 = TestFunction(U2, name='u2')
    w1 = VectorTestFunction(W1, name='w1')
    w2 = VectorTestFunction(W2, name='w2')
    t1 = VectorTestFunction(T1, name='t1')
    t2 = VectorTestFunction(T2, name='t2')

    V = ProductSpace(V1, V2)
    U = ProductSpace(U1, U2)

    x, y = V1.coordinates

    alpha = Constant('alpha')

    F = Field('F', space=V1)

    # ...
    a1 = BilinearForm((v1, u1), u1 * v1, check=True)
    a = BilinearForm((v2, u2), a1(v2, u2), check=True)
    # ...

    # ...
    a = BilinearForm((v1, u1), dot(grad(v1), grad(u1)), check=True)
    # ...

    # ...
    a1 = BilinearForm((v1, u1), dot(grad(v1), grad(u1)), check=True)
    a = BilinearForm((v2, u2), a1(v2, u2), check=True)
    # ...

    # ...
    a1 = BilinearForm((v1, u1), u1 * v1)
    a2 = BilinearForm((v1, u1), dx(u1) * dx(v1), check=True)
    a = BilinearForm((v2, u2), a1(v2, u2) + a2(v2, u2), check=True)
    # ...

    # ...
    a1 = BilinearForm((v1, u1), u1 * v1, check=True)
    a2 = BilinearForm((v1, u1), dx(u1) * dx(v1), check=True)
    # ...

    # ...
    a1 = BilinearForm((v1, u1), u1 * v1, check=True)
    a2 = BilinearForm((v1, u1), dx(u1) * dx(v1), check=True)
    a = BilinearForm(((v1, v2), (u1, u2)), a1(v1, u2) + a2(v2, u1), check=True)
    # ...

    # ...
    a = BilinearForm((w1, t1),
                     rot(w1) * rot(t1) + div(w1) * div(t1),
                     check=True)
    # ...

    # ...
    a1 = BilinearForm((v1, u1), u1 * v1, check=True)
    a2 = BilinearForm((v1, u1), dx(u1) * dx(v1), check=True)
    a3 = BilinearForm((w1, t1),
                      rot(w1) * rot(t1) + div(w1) * div(t1),
                      check=True)
    a4 = BilinearForm((w1, u1), div(w1) * u1, check=True)

    a = BilinearForm(((w2, v2), (t2, u2)),
                     a3(w2, t2) + a2(v2, u2) + a4(w2, u2),
                     check=True)
    # ...

    # ...
    a1 = BilinearForm((v1, u1), laplace(u1) * laplace(v1), check=True)
    # ...

    # ...
    a1 = BilinearForm((v1, u1), inner(hessian(u1), hessian(v1)), check=True)
    # ...

    # ... stokes
    V = VectorFunctionSpace('V', domain)
    W = FunctionSpace('W', domain)

    v = VectorTestFunction(V, name='v')
    u = VectorTestFunction(V, name='u')
    p = TestFunction(W, name='p')
    q = TestFunction(W, name='q')

    a = BilinearForm((v, u), inner(grad(v), grad(u)), check=True)
    b = BilinearForm((v, p), div(v) * p, check=True)
    A = BilinearForm(((v, q), (u, p)), a(v, u) - b(v, p) + b(u, q), check=True)
    # ...

    ################################
    #    non bilinear forms
    ################################
    # ...
    with pytest.raises(UnconsistentLinearExpressionError):
        a = BilinearForm((v1, u1), dot(grad(v1), grad(u1)) + v1, check=True)
    # ...

    # ...
    with pytest.raises(UnconsistentLinearExpressionError):
        a = BilinearForm((v1, u1), v1**2 * u1, check=True)
    # ...

    # ...
    with pytest.raises(UnconsistentLinearExpressionError):
        a = BilinearForm((v1, u1), dot(grad(v1), grad(v1)), check=True)
Пример #18
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def test_Inner(dim):

    domain = Domain('Omega', dim=dim)
    W = VectorFunctionSpace('W', domain)
    a, b, c = elements_of(W, names='a, b, c')
    r = Constant('r')

    # Commutativity
    assert inner(a, b) == inner(b, a)

    # Bilinearity: vector addition
    assert inner(a, b + c) == inner(a, b) + inner(a, c)
    assert inner(a + b, c) == inner(a, c) + inner(b, c)

    # Bilinearity: scalar multiplication
    assert inner(a, r * b) == r * inner(a, b)
    assert inner(r * a, b) == r * inner(a, b)

    # Special case: null vector
    assert inner(a, 0) == 0
    assert inner(0, a) == 0

    # Special case: two arguments are the same
    assert inner(a, a).is_real
    assert inner(a, a).is_positive
Пример #19
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def test_calls_2d():
    domain = Domain('Omega', dim=DIM)

    V1 = FunctionSpace('V1', domain)
    V2 = FunctionSpace('V2', domain)
    U1 = FunctionSpace('U1', domain)
    U2 = FunctionSpace('U2', domain)
    W1 = VectorFunctionSpace('W1', domain)
    W2 = VectorFunctionSpace('W2', domain)
    T1 = VectorFunctionSpace('T1', domain)
    T2 = VectorFunctionSpace('T2', domain)

    v1 = TestFunction(V1, name='v1')
    v2 = TestFunction(V2, name='v2')
    u1 = TestFunction(U1, name='u1')
    u2 = TestFunction(U2, name='u2')
    w1 = VectorTestFunction(W1, name='w1')
    w2 = VectorTestFunction(W2, name='w2')
    t1 = VectorTestFunction(T1, name='t1')
    t2 = VectorTestFunction(T2, name='t2')

    V = ProductSpace(V1, V2)
    U = ProductSpace(U1, U2)

    x, y = V1.coordinates

    alpha = Constant('alpha')

    F = Field('F', space=V1)

    # ...
    a1 = BilinearForm((v1, u1), u1 * v1, name='a1')
    print(a1)
    print(atomize(a1))
    print(evaluate(a1))
    print('')

    expr = a1(v2, u2)
    a = BilinearForm((v2, u2), expr, name='a')
    print(a)
    print(atomize(a))
    print(evaluate(a))
    print('')
    # ...

    # ...
    a = BilinearForm((v1, u1), dot(grad(v1), grad(u1)), name='a')

    print(a)
    print(atomize(a))
    print(evaluate(a))
    print('')
    # ...

    # ...
    a1 = BilinearForm((v1, u1), dot(grad(v1), grad(u1)), name='a1')

    expr = a1(v2, u2)
    a = BilinearForm((v2, u2), expr, name='a')
    print(a)
    print(atomize(a))
    print(evaluate(a))
    print('')
    # ...

    # ...
    a1 = BilinearForm((v1, u1), u1 * v1, name='a1')
    a2 = BilinearForm((v1, u1), dx(u1) * dx(v1), name='a2')

    expr = a1(v2, u2) + a2(v2, u2)
    a = BilinearForm((v2, u2), expr, name='a')
    print(a)
    print(atomize(a))
    print(evaluate(a))
    print('')
    # ...

    # ...
    a1 = BilinearForm((v1, u1), u1 * v1, name='a1')
    a2 = BilinearForm((v1, u1), dx(u1) * dx(v1), name='a2')

    expr = a1(v1, u2)
    print('> before = ', expr)
    expr = expr.subs(u2, u1)
    print('> after  = ', expr)
    print('')

    expr = a1(v1, u2) + a1(v2, u2)
    print('> before = ', expr)
    expr = expr.subs(u2, u1)
    print('> after  = ', expr)
    print('')
    # ...

    # ...
    a1 = BilinearForm((v1, u1), u1 * v1, name='a1')
    a2 = BilinearForm((v1, u1), dx(u1) * dx(v1), name='a2')

    expr = a1(v1, u2) + a2(v2, u1)
    a = BilinearForm(((v1, v2), (u1, u2)), expr, name='a')
    print(a)
    print(atomize(a))
    print(evaluate(a))
    print('')
    # ...

    # ...
    a = BilinearForm((w1, t1), rot(w1) * rot(t1) + div(w1) * div(t1), name='a')
    print(a)
    print(atomize(a))
    print(evaluate(a))
    # ...

    # ...
    a1 = BilinearForm((v1, u1), u1 * v1, name='a1')
    a2 = BilinearForm((v1, u1), dx(u1) * dx(v1), name='a2')
    a3 = BilinearForm((w1, t1),
                      rot(w1) * rot(t1) + div(w1) * div(t1),
                      name='a3')
    a4 = BilinearForm((w1, u1), div(w1) * u1, name='a4')

    expr = a3(w2, t2) + a2(v2, u2) + a4(w2, u2)
    a = BilinearForm(((w2, v2), (t2, u2)), expr, name='a')
    print(a)
    print(atomize(a))
    print(evaluate(a))
    # ...

    # ...
    a1 = BilinearForm((v1, u1), laplace(u1) * laplace(v1), name='a1')
    print(a1)
    print(atomize(a1))
    print(evaluate(a1))
    print('')
    # ...

    # ...
    a1 = BilinearForm((v1, u1), inner(hessian(u1), hessian(v1)), name='a1')
    print('================================')
    print(a1)
    print(atomize(a1))
    print(evaluate(a1))
    print('')
    # ...

    # ...
    l1 = LinearForm(v1, x * y * v1, name='11')

    expr = l1(v2)
    l = LinearForm(v2, expr, name='1')
    print(l)
    print(atomize(l))
    print(evaluate(l))
    # ...

    # ...
    l1 = LinearForm(v1, x * y * v1, name='l1')
    l2 = LinearForm(v2, cos(x + y) * v2, name='l2')

    expr = l1(u1) + l2(u2)
    l = LinearForm((u1, u2), expr, name='1')
    print(l)
    print(atomize(l))
    print(evaluate(l))
    # ...

    # ...
    l1 = LinearForm(v1, x * y * v1, name='l1')
    l2 = LinearForm(v2, cos(x + y) * v2, name='l2')

    expr = l1(u1) + alpha * l2(u2)
    l = LinearForm((u1, u2), expr, name='1')
    print(l)
    print(atomize(l))
    print(evaluate(l))
    # ...

    # ...
    l1 = LinearForm(v1, x * y * v1, name='l1')
    l2 = LinearForm(w1, div(w1), name='l2')

    expr = l1(v2) + l2(w2)
    l = LinearForm((v2, w2), expr, name='1')
    print(l)
    print(atomize(l))
    print(evaluate(l))
    # ...

    # ...
    I1 = Integral(x * y, domain, name='I1')

    print(I1)
    print(atomize(I1))
    print(evaluate(I1))
    # ...

    # ...
    expr = F - cos(2 * pi * x) * cos(3 * pi * y)
    expr = dot(grad(expr), grad(expr))
    I2 = Integral(expr, domain, name='I2')

    print(I2)
    print(atomize(I2))
    print(evaluate(I2))
    # ...

    # ...
    expr = F - cos(2 * pi * x) * cos(3 * pi * y)
    expr = dot(grad(expr), grad(expr))
    I2 = Integral(expr, domain, name='I2')

    print(I2)
    print(atomize(I2))
    print(evaluate(I2))
    # ...

    # ... stokes
    V = VectorFunctionSpace('V', domain)
    W = FunctionSpace('W', domain)

    v = VectorTestFunction(V, name='v')
    u = VectorTestFunction(V, name='u')
    p = TestFunction(W, name='p')
    q = TestFunction(W, name='q')

    a = BilinearForm((v, u), inner(grad(v), grad(u)), name='a')
    b = BilinearForm((v, p), div(v) * p, name='b')
    A = BilinearForm(((v, q), (u, p)), a(v, u) - b(v, p) + b(u, q), name='A')

    print(A)
    print(atomize(A))
    print(evaluate(A))