Bests,
Reza
----- Original Message ----
From: Mehdi Nikbakht <M.Nikbakht@xxxxxxxxxx>
To: Reza Farrahi Moghaddam <imriss@xxxxxxxxx>
Sent: Monday, April 14, 2008 10:03:27 AM
Subject: Re: [FFC-dev] source term in bilinear form
Hello,
Since in your bilinearform, you have two functions(U0 and f), then you
need to
call "NonlinearPoissonBilinearForm" with two arguments.
regards,
--
Mehdi
Quoting Reza Farrahi Moghaddam <imriss@xxxxxxxxx <mailto:imriss@xxxxxxxxx>>:
> Hello,
>
> I am not sure if this post fits the ffc-dev list, but I would be
grateful if
> you send me some suggestions.
>
> I want to use dolfin/ffc for solving image processing problems. I
start from
> Nonlinear Poisson demo. After linearization of the governing weak
equation,
> the input form file is as follows:
> element = FiniteElement("Lagrange", "triangle", 1)
> v = TestFunction(element)
> U = TrialFunction(element)
> U0= Function(element)
> f = Function(element)
> a = -v*(U0-f)*dot(grad(U0),grad(U))*dx
> L = v*(0.01+dot(grad(U0),grad(U0)))*(U0-f)*dx +
> 0.01*dot(grad(v),grad(U0))*dx
>
> The "f" represents the input image (at moment only a simple analytic
function
> is used). The form file compiles well, but when I try to make the main
> program, there are some errors on NonlinearPoissonBilinearForm matching.
> The complete log of make:
> [rfarahi@alteran cpp]$ make
> `pkg-config --variable=compiler dolfin` `pkg-config --cflags dolfin` -c
> main.cpp
> main.cpp: In function `int main(int, char**)':
> main.cpp:89: error: no matching function for call to
>
`NonlinearPoissonBilinearForm::NonlinearPoissonBilinearForm(dolfin::Function&)'
> NonlinearPoisson.h:4672: note: candidates are:
> NonlinearPoissonBilinearForm::NonlinearPoissonBilinearForm(const
> NonlinearPoissonBilinearForm&)
> NonlinearPoisson.h:4675: note:
>
NonlinearPoissonBilinearForm::NonlinearPoissonBilinearForm(dolfin::Function&,
> dolfin::Function&)
> mpic++: No such file or directory
> make: *** [main.o] Error 1
>
>
> If I change the script and delete the "f" term from the bilinear
form, the
> error doesn't show up:
> element = FiniteElement("Lagrange", "triangle", 1)
> v = TestFunction(element)
> U = TrialFunction(element)
> U0= Function(element)
> f = Function(element)
> a = -v*(U0)*dot(grad(U0),grad(U))*dx
> L = v*(0.01+dot(grad(U0),grad(U0)))*(U0-f)*dx +
> 0.01*dot(grad(v),grad(U0))*dx
>
> The input cpp file:
> // Copyright (C) 2006-2007 Garth N. Wells.
> // Licensed under the GNU LGPL Version 2.1.
> //
> // Modified by Anders Logg, 2005
> //
> // First added: 2005
> // Last changed: 2007-08-20
> //
>
> #include <dolfin.h>
> #include "NonlinearPoisson.h"
>
> using namespace dolfin;
> // Right-hand side
> class Source : public Function
> {
> public:
> Source(Mesh& mesh) : Function(mesh) {}
> real eval(const real* x) const
> {
> return x[0];
> }
> };
> // Dirichlet boundary condition
> class DirichletBoundaryCondition : public Function, public TimeDependent
> {
> public:
> DirichletBoundaryCondition(Mesh& mesh, real& t) : Function(mesh),
> TimeDependent(t) {}
> real eval(const real* x) const
> {
> return 1.0;
> }
> };
> // Sub domain for Dirichlet boundary condition
> class DirichletBoundary : public SubDomain
> {
> bool inside(const real* x, bool on_boundary) const
> {
> return std::abs(x[0] - 1.0) < DOLFIN_EPS && on_boundary;
> }
> };
> int main(int argc, char* argv[])
> {
> dolfin_init(argc, argv);
>
> // Set up problem
> UnitSquare mesh(16, 16);
> // Pseudo time
> real t = 0.0;
> // Create source function
> Source f(mesh);
> // Dirichlet boundary conditions
> DirichletBoundary dirichlet_boundary;
> DirichletBoundaryCondition g(mesh, t);
> DirichletBC bc(g, mesh, dirichlet_boundary);
> // Solution function
> Function u;
> // Create forms and nonlinear PDE
> NonlinearPoissonBilinearForm a(u);
> NonlinearPoissonLinearForm L(u, f);
> NonlinearPDE pde(a, L, mesh, bc);
> // Solve nonlinear problem in a series of steps
> real dt = 1.0; real T = 3.0;
> // pde.dolfin_set("Newton relative tolerance", 1e-6);
> // pde.dolfin_set("Newton convergence criterion", "incremental");
> // Solve
> pde.solve(u, t, T, dt);
> // Plot solution
> plot(u);
> // Save function to file
> File file("nonlinear_poisson.pvd");
> file << u;
> return 0;
> }
>
>
>
>
> Any suggestion?
>
> Bests,
> Reza
>
>
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