Esempio n. 1
0
def foo():
    m = 4

    errL2u = np.zeros((m - 1, 1))
    errH1u = np.zeros((m - 1, 1))
    errL2p = np.zeros((m - 1, 1))
    errL2b = np.zeros((m - 1, 1))
    errCurlb = np.zeros((m - 1, 1))
    errL2r = np.zeros((m - 1, 1))
    errH1r = np.zeros((m - 1, 1))

    l2uorder = np.zeros((m - 1, 1))
    H1uorder = np.zeros((m - 1, 1))
    l2porder = np.zeros((m - 1, 1))
    l2border = np.zeros((m - 1, 1))
    Curlborder = np.zeros((m - 1, 1))
    l2rorder = np.zeros((m - 1, 1))
    H1rorder = np.zeros((m - 1, 1))

    NN = np.zeros((m - 1, 1))
    DoF = np.zeros((m - 1, 1))
    Velocitydim = np.zeros((m - 1, 1))
    Magneticdim = np.zeros((m - 1, 1))
    Pressuredim = np.zeros((m - 1, 1))
    Lagrangedim = np.zeros((m - 1, 1))
    Wdim = np.zeros((m - 1, 1))
    iterations = np.zeros((m - 1, 1))
    SolTime = np.zeros((m - 1, 1))
    udiv = np.zeros((m - 1, 1))
    MU = np.zeros((m - 1, 1))
    level = np.zeros((m - 1, 1))
    NSave = np.zeros((m - 1, 1))
    Mave = np.zeros((m - 1, 1))
    TotalTime = np.zeros((m - 1, 1))

    nn = 2

    dim = 2
    ShowResultPlots = 'yes'
    split = 'Linear'

    MU[0] = 1e0
    for xx in xrange(1, m):
        print xx
        level[xx - 1] = xx + 0
        nn = 2**(level[xx - 1])

        # Create mesh and define function space
        nn = int(nn)
        NN[xx - 1] = nn / 2
        # parameters["form_compiler"]["quadrature_degree"] = 6
        # parameters = CP.ParameterSetup()
        mesh = UnitSquareMesh(nn, nn)

        order = 2
        parameters['reorder_dofs_serial'] = False
        Velocity = VectorFunctionSpace(mesh, "CG", order)
        Pressure = FunctionSpace(mesh, "CG", order - 1)
        Magnetic = FunctionSpace(mesh, "N1curl", order - 1)
        Lagrange = FunctionSpace(mesh, "CG", order - 1)
        W = MixedFunctionSpace([Velocity, Pressure, Magnetic, Lagrange])
        # W = Velocity*Pressure*Magnetic*Lagrange
        Velocitydim[xx - 1] = Velocity.dim()
        Pressuredim[xx - 1] = Pressure.dim()
        Magneticdim[xx - 1] = Magnetic.dim()
        Lagrangedim[xx - 1] = Lagrange.dim()
        Wdim[xx - 1] = W.dim()
        print "\n\nW:  ", Wdim[xx - 1], "Velocity:  ", Velocitydim[
            xx -
            1], "Pressure:  ", Pressuredim[xx - 1], "Magnetic:  ", Magneticdim[
                xx - 1], "Lagrange:  ", Lagrangedim[xx - 1], "\n\n"
        dim = [Velocity.dim(), Pressure.dim(), Magnetic.dim(), Lagrange.dim()]

        def boundary(x, on_boundary):
            return on_boundary

        u0, p0, b0, r0, Laplacian, Advection, gradPres, CurlCurl, gradR, NS_Couple, M_Couple = ExactSol.MHD2D(
            4, 1, mesh)

        bcu = DirichletBC(Velocity, u0, boundary)
        bcb = DirichletBC(Magnetic, b0, boundary)
        bcr = DirichletBC(Lagrange, r0, boundary)

        # bc = [u0,p0,b0,r0]
        bcs = [bcu, bcb, bcr]
        FSpaces = [Velocity, Pressure, Magnetic, Lagrange]

        (u, b, p, r) = TrialFunctions(W)
        (v, c, q, s) = TestFunctions(W)
        kappa = 10.0
        Mu_m = 10.0
        MU = 1.0 / 1
        IterType = 'Full'
        Split = "No"
        Saddle = "No"
        Stokes = "No"
        SetupType = 'python-class'
        F_NS = -MU * Laplacian + Advection + gradPres - kappa * NS_Couple
        if kappa == 0:
            F_M = Mu_m * CurlCurl + gradR - kappa * M_Couple
        else:
            F_M = Mu_m * kappa * CurlCurl + gradR - kappa * M_Couple
        params = [kappa, Mu_m, MU]

        MO.PrintStr("Seting up initial guess matricies", 2, "=", "\n\n", "\n")
        BCtime = time.time()
        BC = MHDsetup.BoundaryIndices(mesh)
        MO.StrTimePrint("BC index function, time: ", time.time() - BCtime)
        Hiptmairtol = 1e-6
        HiptmairMatrices = PrecondSetup.MagneticSetup(Magnetic, Lagrange, b0,
                                                      r0, Hiptmairtol, params)

        MO.PrintStr("Setting up MHD initial guess", 5, "+", "\n\n", "\n\n")
        u_k, p_k, b_k, r_k = common.InitialGuess(FSpaces, [u0, p0, b0, r0],
                                                 [F_NS, F_M],
                                                 params,
                                                 HiptmairMatrices,
                                                 1e-10,
                                                 Neumann=Expression(
                                                     ("0", "0")),
                                                 options="New")
        b_t = TrialFunction(Velocity)
        c_t = TestFunction(Velocity)

        ones = Function(Pressure)
        ones.vector()[:] = (0 * ones.vector().array() + 1)
        # pConst = - assemble(p_k*dx)/assemble(ones*dx)
        p_k.vector()[:] += -assemble(p_k * dx) / assemble(ones * dx)
        x = Iter.u_prev(u_k, p_k, b_k, r_k)

        KSPlinearfluids, MatrixLinearFluids = PrecondSetup.FluidLinearSetup(
            Pressure, MU)
        kspFp, Fp = PrecondSetup.FluidNonLinearSetup(Pressure, MU, u_k)
        #plot(b_k)

        ns, maxwell, CoupleTerm, Lmaxwell, Lns = forms.MHD2D(
            mesh, W, F_M, F_NS, u_k, b_k, params, IterType, "CG", Saddle,
            Stokes)
        RHSform = forms.PicardRHS(mesh, W, u_k, p_k, b_k, r_k, params, "CG",
                                  Saddle, Stokes)

        bcu = DirichletBC(W.sub(0), Expression(("0.0", "0.0")), boundary)
        bcb = DirichletBC(W.sub(2), Expression(("0.0", "0.0")), boundary)
        bcr = DirichletBC(W.sub(3), Expression(("0.0")), boundary)
        bcs = [bcu, bcb, bcr]

        parameters['linear_algebra_backend'] = 'uBLAS'

        eps = 1.0  # error measure ||u-u_k||
        tol = 1.0E-4  # tolerance
        iter = 0  # iteration counter
        maxiter = 10  # max no of iterations allowed
        SolutionTime = 0
        outer = 0
        # parameters['linear_algebra_backend'] = 'uBLAS'

        # FSpaces = [Velocity,Magnetic,Pressure,Lagrange]

        if IterType == "CD":
            MO.PrintStr("Setting up PETSc " + SetupType, 2, "=", "\n", "\n")
            Alin = MHDsetup.Assemble(W, ns, maxwell, CoupleTerm, Lns, Lmaxwell,
                                     RHSform, bcs + BC, "Linear", IterType)
            Fnlin, b = MHDsetup.Assemble(W, ns, maxwell, CoupleTerm, Lns,
                                         Lmaxwell, RHSform, bcs + BC,
                                         "NonLinear", IterType)
            A = Fnlin + Alin
            A, b = MHDsetup.SystemAssemble(FSpaces, A, b, SetupType, IterType)
            u = b.duplicate()

        u_is = PETSc.IS().createGeneral(range(Velocity.dim()))
        NS_is = PETSc.IS().createGeneral(range(Velocity.dim() +
                                               Pressure.dim()))
        M_is = PETSc.IS().createGeneral(
            range(Velocity.dim() + Pressure.dim(), W.dim()))
        OuterTol = 1e-5
        InnerTol = 1e-5
        NSits = 0
        Mits = 0
        TotalStart = time.time()
        SolutionTime = 0
        while eps > tol and iter < maxiter:
            iter += 1
            MO.PrintStr("Iter " + str(iter), 7, "=", "\n\n", "\n\n")
            AssembleTime = time.time()
            if IterType == "CD":
                MO.StrTimePrint("MHD CD RHS assemble, time: ",
                                time.time() - AssembleTime)
                b = MHDsetup.Assemble(W, ns, maxwell, CoupleTerm, Lns,
                                      Lmaxwell, RHSform, bcs + BC, "CD",
                                      IterType)
            else:
                MO.PrintStr("Setting up PETSc " + SetupType, 2, "=", "\n",
                            "\n")
                if Split == "Yes":
                    if iter == 1:
                        Alin = MHDsetup.Assemble(W, ns, maxwell, CoupleTerm,
                                                 Lns, Lmaxwell, RHSform,
                                                 bcs + BC, "Linear", IterType)
                        Fnlin, b = MHDsetup.Assemble(W, ns, maxwell,
                                                     CoupleTerm, Lns, Lmaxwell,
                                                     RHSform, bcs + BC,
                                                     "NonLinear", IterType)
                        A = Fnlin + Alin
                        A, b = MHDsetup.SystemAssemble(FSpaces, A, b,
                                                       SetupType, IterType)
                        u = b.duplicate()
                    else:
                        Fnline, b = MHDsetup.Assemble(W, ns, maxwell,
                                                      CoupleTerm, Lns,
                                                      Lmaxwell, RHSform,
                                                      bcs + BC, "NonLinear",
                                                      IterType)
                        A = Fnlin + Alin
                        A, b = MHDsetup.SystemAssemble(FSpaces, A, b,
                                                       SetupType, IterType)
                else:
                    AA, bb = assemble_system(maxwell + ns + CoupleTerm,
                                             (Lmaxwell + Lns) - RHSform, bcs)
                    A, b = CP.Assemble(AA, bb)
            # if iter == 1:
            MO.StrTimePrint("MHD total assemble, time: ",
                            time.time() - AssembleTime)

            u = b.duplicate()
            kspFp, Fp = PrecondSetup.FluidNonLinearSetup(Pressure, MU, u_k)
            print "Inititial guess norm: ", u.norm(
                PETSc.NormType.NORM_INFINITY)
            #A,Q
            if IterType == 'Full':

                n = FacetNormal(mesh)
                mat = as_matrix([[b_k[1] * b_k[1], -b_k[1] * b_k[0]],
                                 [-b_k[1] * b_k[0], b_k[0] * b_k[0]]])
                a = params[2] * inner(grad(b_t), grad(c_t)) * dx(
                    W.mesh()) + inner((grad(b_t) * u_k), c_t) * dx(W.mesh(
                    )) + (1. / 2) * div(u_k) * inner(c_t, b_t) * dx(
                        W.mesh()) - (1. / 2) * inner(u_k, n) * inner(
                            c_t, b_t) * ds(W.mesh()) + kappa / Mu_m * inner(
                                mat * b_t, c_t) * dx(W.mesh())
                ShiftedMass = assemble(a)
                bcu.apply(ShiftedMass)
                ShiftedMass = CP.Assemble(ShiftedMass)
                kspF = NSprecondSetup.LSCKSPnonlinear(ShiftedMass)
            else:
                F = A.getSubMatrix(u_is, u_is)
                kspF = NSprecondSetup.LSCKSPnonlinear(F)

            aVec, L_M, L_NS, Bt, CoupleT = forms.MHDmatvec(mesh,
                                                           W,
                                                           Laplacian,
                                                           Laplacian,
                                                           u_k,
                                                           b_k,
                                                           u,
                                                           b,
                                                           p,
                                                           r,
                                                           params,
                                                           "Full",
                                                           "CG",
                                                           SaddlePoint="No")
            bcu = DirichletBC(Velocity, u0, boundary)
            PrecondTmult = {'Bt': Bt, 'Ct': CoupleT, 'BC': bcu}
            FS = {
                'velocity': Velocity,
                'pressure': Pressure,
                'magnetic': Magnetic,
                'multiplier': Lagrange
            }
            P = PETSc.Mat().createPython([W.dim(), W.dim()])
            P.setType('python')
            aa = MHDmulti.PetscMatVec(FS, aVec, bcs, PrecondTmult)
            P.setPythonContext(aa)
            P.setUp()
            stime = time.time()
            u, mits, nsits = S.solve(A, P, b, u, params, W, 'Directsss',
                                     IterType, OuterTol, InnerTol,
                                     HiptmairMatrices, Hiptmairtol,
                                     KSPlinearfluids, Fp, kspF)
            Soltime = time.time() - stime
            MO.StrTimePrint("MHD solve, time: ", Soltime)
            Mits += mits
            NSits += nsits
            SolutionTime += Soltime

            u1, p1, b1, r1, eps = Iter.PicardToleranceDecouple(
                u, x, FSpaces, dim, "2", iter)
            p1.vector()[:] += -assemble(p1 * dx) / assemble(ones * dx)
            u_k.assign(u1)
            p_k.assign(p1)
            b_k.assign(b1)
            r_k.assign(r1)
            uOld = np.concatenate((u_k.vector().array(), p_k.vector().array(),
                                   b_k.vector().array(), r_k.vector().array()),
                                  axis=0)
            x = IO.arrayToVec(uOld)

        XX = np.concatenate((u_k.vector().array(), p_k.vector().array(),
                             b_k.vector().array(), r_k.vector().array()),
                            axis=0)
        SolTime[xx - 1] = SolutionTime / iter
        NSave[xx - 1] = (float(NSits) / iter)
        Mave[xx - 1] = (float(Mits) / iter)
        iterations[xx - 1] = iter
        TotalTime[xx - 1] = time.time() - TotalStart
    #     dim = [Velocity.dim(), Pressure.dim(), Magnetic.dim(),Lagrange.dim()]

    #     ExactSolution = [u0,p0,b0,r0]
    #     errL2u[xx-1], errH1u[xx-1], errL2p[xx-1], errL2b[xx-1], errCurlb[xx-1], errL2r[xx-1], errH1r[xx-1] = Iter.Errors(XX,mesh,FSpaces,ExactSolution,order,dim, "DG")

    #     if xx > 1:
    #        l2uorder[xx-1] =  np.abs(np.log2(errL2u[xx-2]/errL2u[xx-1]))
    #        H1uorder[xx-1] =  np.abs(np.log2(errH1u[xx-2]/errH1u[xx-1]))

    #        l2porder[xx-1] =  np.abs(np.log2(errL2p[xx-2]/errL2p[xx-1]))

    #        l2border[xx-1] =  np.abs(np.log2(errL2b[xx-2]/errL2b[xx-1]))
    #        Curlborder[xx-1] =  np.abs(np.log2(errCurlb[xx-2]/errCurlb[xx-1]))

    #        l2rorder[xx-1] =  np.abs(np.log2(errL2r[xx-2]/errL2r[xx-1]))
    #        H1rorder[xx-1] =  np.abs(np.log2(errH1r[xx-2]/errH1r[xx-1]))

    # import pandas as pd

    # LatexTitles = ["l","DoFu","Dofp","V-L2","L2-order","V-H1","H1-order","P-L2","PL2-order"]
    # LatexValues = np.concatenate((level,Velocitydim,Pressuredim,errL2u,l2uorder,errH1u,H1uorder,errL2p,l2porder), axis=1)
    # LatexTable = pd.DataFrame(LatexValues, columns = LatexTitles)
    # pd.set_option('precision',3)
    # LatexTable = MO.PandasFormat(LatexTable,"V-L2","%2.4e")
    # LatexTable = MO.PandasFormat(LatexTable,'V-H1',"%2.4e")
    # LatexTable = MO.PandasFormat(LatexTable,"H1-order","%1.2f")
    # LatexTable = MO.PandasFormat(LatexTable,'L2-order',"%1.2f")
    # LatexTable = MO.PandasFormat(LatexTable,"P-L2","%2.4e")
    # LatexTable = MO.PandasFormat(LatexTable,'PL2-order',"%1.2f")
    # print LatexTable

    # print "\n\n   Magnetic convergence"
    # MagneticTitles = ["l","B DoF","R DoF","B-L2","L2-order","B-Curl","HCurl-order"]
    # MagneticValues = np.concatenate((level,Magneticdim,Lagrangedim,errL2b,l2border,errCurlb,Curlborder),axis=1)
    # MagneticTable= pd.DataFrame(MagneticValues, columns = MagneticTitles)
    # pd.set_option('precision',3)
    # MagneticTable = MO.PandasFormat(MagneticTable,"B-Curl","%2.4e")
    # MagneticTable = MO.PandasFormat(MagneticTable,'B-L2',"%2.4e")
    # MagneticTable = MO.PandasFormat(MagneticTable,"L2-order","%1.2f")
    # MagneticTable = MO.PandasFormat(MagneticTable,'HCurl-order',"%1.2f")
    # print MagneticTable

    # print "\n\n   Lagrange convergence"
    # LagrangeTitles = ["l","B DoF","R DoF","R-L2","L2-order","R-H1","H1-order"]
    # LagrangeValues = np.concatenate((level,Lagrangedim,Lagrangedim,errL2r,l2rorder,errH1r,H1rorder),axis=1)
    # LagrangeTable= pd.DataFrame(LagrangeValues, columns = LagrangeTitles)
    # pd.set_option('precision',3)
    # LagrangeTable = MO.PandasFormat(LagrangeTable,"R-L2","%2.4e")
    # LagrangeTable = MO.PandasFormat(LagrangeTable,'R-H1',"%2.4e")
    # LagrangeTable = MO.PandasFormat(LagrangeTable,"L2-order","%1.2f")
    # LagrangeTable = MO.PandasFormat(LagrangeTable,'H1-order',"%1.2f")
    # print LagrangeTable

    import pandas as pd

    print "\n\n   Iteration table"
    if IterType == "Full":
        IterTitles = [
            "l",
            "DoF",
            "AV solve Time",
            "Total picard time",
            "picard iterations",
            "Av Outer its",
            "Av Inner its",
        ]
    else:
        IterTitles = [
            "l", "DoF", "AV solve Time", "Total picard time",
            "picard iterations", "Av NS iters", "Av M iters"
        ]
    IterValues = np.concatenate(
        (level, Wdim, SolTime, TotalTime, iterations, Mave, NSave), axis=1)
    IterTable = pd.DataFrame(IterValues, columns=IterTitles)
    if IterType == "Full":
        IterTable = MO.PandasFormat(IterTable, 'Av Outer its', "%2.1f")
        IterTable = MO.PandasFormat(IterTable, 'Av Inner its', "%2.1f")
    else:
        IterTable = MO.PandasFormat(IterTable, 'Av NS iters', "%2.1f")
        IterTable = MO.PandasFormat(IterTable, 'Av M iters', "%2.1f")
    print IterTable
    print " \n  Outer Tol:  ", OuterTol, "Inner Tol:   ", InnerTol

    #    tableName = "2d_nu="+str(MU)+"_nu_m="+str(Mu_m)+"_kappa="+str(kappa)+"_l="+str(np.min(level))+"-"+str(np.max(level))+".tex"
    #    IterTable.to_latex(tableName)

    # # # if (ShowResultPlots == 'yes'):

    #    plot(u_k)
    #    plot(interpolate(u0,Velocity))
    #
    #    plot(p_k)
    #
    #    plot(interpolate(p0,Pressure))
    #
    #    plot(b_k)
    #    plot(interpolate(b0,Magnetic))
    #
    #    plot(r_k)
    #    plot(interpolate(r0,Lagrange))
    #
    #    interactive()

    interactive()
Esempio n. 2
0
def foo():
    m = 5
    errL2u = np.zeros((m - 1, 1))
    errL2p = np.zeros((m - 1, 1))
    l2uorder = np.zeros((m - 1, 1))
    l2porder = np.zeros((m - 1, 1))
    NN = np.zeros((m - 1, 1))
    DoF = np.zeros((m - 1, 1))
    Vdim = np.zeros((m - 1, 1))
    Qdim = np.zeros((m - 1, 1))
    Wdim = np.zeros((m - 1, 1))
    iterations = np.zeros((m - 1, 1))
    SolTime = np.zeros((m - 1, 1))
    udiv = np.zeros((m - 1, 1))
    nn = 2

    dim = 2
    Solving = 'Direct'
    ShowResultPlots = 'no'
    ShowErrorPlots = 'no'
    EigenProblem = 'no'
    SavePrecond = 'no'
    case = 1
    parameters['linear_algebra_backend'] = 'uBLAS'

    for xx in xrange(1, m):
        print xx
        nn = 2**(xx + 0)
        # Create mesh and define function space
        nn = int(nn)
        NN[xx - 1] = nn

        # mesh = UnitSquareMesh(nn,nn)
        mesh = UnitCubeMesh(nn, nn, nn)
        parameters['reorder_dofs_serial'] = False
        V = VectorFunctionSpace(mesh, "CG", 2)
        Q = FunctionSpace(mesh, "CG", 1)
        C = FunctionSpace(mesh, "N1curl", 1)
        S = FunctionSpace(mesh, "CG", 1)
        W = MixedFunctionSpace([V, Q, C, S])

        def boundary(x, on_boundary):
            return on_boundary

        print "               DOFs              ", W.dim()
        u0, p0, b0, r0, Laplacian, Advection, gradPres, CurlCurl, gradR, NS_Couple, M_Couple = ExactSol.MHD3D(
            4, 1, mesh)
        dim = Laplacian.shape()[0]

        n = FacetNormal(mesh)
        bcu = DirichletBC(V, u0, boundary)
        bcb = DirichletBC(C, b0, boundary)
        bcr = DirichletBC(S, r0, boundary)

        u_k = Function(V)
        u_k.vector()[:] = np.random.rand(V.dim())
        bcu.apply(u_k.vector())
        p_k = Function(Q)
        p_k.vector()[:] = np.random.rand(Q.dim())
        b_k = Function(C)
        b_k.vector()[:] = np.random.rand(C.dim())
        bcb.apply(b_k.vector())
        r_k = Function(S)
        r_k.vector()[:] = np.random.rand(S.dim())
        bcr.apply(r_k.vector())

        B = np.concatenate((u_k.vector().array(), p_k.vector().array(),
                            b_k.vector().array(), r_k.vector().array()),
                           axis=0)
        x = arrayToVec(B)

        (u, p, b, r) = TrialFunctions(W)
        (v, q, c, s) = TestFunctions(W)

        m11 = inner(curl(b), curl(c)) * dx
        m22 = inner(r, s) * dx
        m21 = inner(c, grad(r)) * dx
        m12 = inner(b, grad(s)) * dx
        # Lmaxwell  = inner(c, F_M)*dx

        a11 = inner(grad(v), grad(u)) * dx(mesh) + inner(
            (grad(u) * u_k), v) * dx(mesh) + (1. / 2) * div(u_k) * inner(
                u, v) * dx(mesh) - (1. / 2) * inner(u_k, n) * inner(
                    u, v) * ds(mesh)
        a12 = -div(v) * p * dx
        a21 = -div(u) * q * dx
        # Lns  = inner(v, F_NS)*dx

        if dim == 2:
            CoupleT = (v[0] * b_k[1] - v[1] * b_k[0]) * curl(b) * dx
            Couple = -(u[0] * b_k[1] - u[1] * b_k[0]) * curl(c) * dx
        elif dim == 3:
            CoupleT = inner(cross(v, b_k), curl(b)) * dx
            Couple = -inner(cross(u, b_k), curl(c)) * dx

        a = m11 + m12 + m21 + a11 + a12 + a21 + Couple + CoupleT

        bcu = DirichletBC(W.sub(0), u0, boundary)
        bcb = DirichletBC(W.sub(2), b0, boundary)
        bcr = DirichletBC(W.sub(3), r0, boundary)
        bcs = [bcu, bcb, bcr]

        tic()

        params = [1, 1, 1]
        aVec, L_M, L_NS, Bt, CoupleT = BiLinear.MHDmatvec(mesh,
                                                          W,
                                                          Laplacian,
                                                          Laplacian,
                                                          u_k,
                                                          b_k,
                                                          u_k,
                                                          b_k,
                                                          p_k,
                                                          r_k,
                                                          params,
                                                          "Full",
                                                          "CG",
                                                          SaddlePoint="No")
        PrecondTmult = {
            'Bt': Bt,
            'Ct': CoupleT,
            'BC': DirichletBC(V, u0, boundary)
        }
        FS = {'velocity': V, 'pressure': Q, 'magnetic': C, 'multiplier': S}
        P = PETSc.Mat().createPython([W.dim(), W.dim()])
        P.setType('python')
        aa = MHDmult.MatVec(FS, aVec, bcs)
        P.setPythonContext(aa)
        P.setUp()
        for i in range(50):
            v = x.duplicate()
            P.mult(x, v)
            # print A.array()
        print '                                      ', toc()

        tic()
        AA = assemble(a)
        for bc in bcs:
            bc.apply(AA)
        # bc.apply(AA)
        A = CP.Assemble(AA)
        # bb.set(1)
        for i in range(50):
            # A = CP.Assemble(A)
            for bc in bcs:
                bc.apply(AA)
            u = x.duplicate()
            A.mult(x, u)

        print '                                      ', toc()

        # print b_k.vector().array()
        # a = inner(grad(v), grad(b_k))*dx
        print np.linalg.norm(u.array - v.array, ord=np.inf)