Arun, > I am implementing a nonlinear equation with time in second derivative. The > weak form has a form like the following (phi is the test function). > > ....... .. φ.Un-1.Un - φ. Un-2.Un-1
I'm not entirely sure I understand what you mean by this. Can you elaborate which equation this corresponds to? Certainly, if you have a nonlinear term for the time derivative, e.g. (u^2+1) d_t^2 u then the mass matrix you need to invert in every time step depends on the previous time step, but I'm not sure whether that's the problem you have. W. ------------------------------------------------------------------------- Wolfgang Bangerth email: [email protected] www: http://www.math.tamu.edu/~bangerth/ _______________________________________________ dealii mailing list http://poisson.dealii.org/mailman/listinfo/dealii
