On Aug 23 2007, Jake Ostien wrote: >Hi, > >I am trying to compute some reaction forces, currently I am trying to >assemble the stiffness matrix and compute the matrix vector product with >the converged solution vector to get a vector of forces. Here is what I >am trying. > ><u is the converged solution> >Matrix A; >assemble(A, *a, mesh); >Vector f; >A.mat().mult(u.vector().vec(), f.vec()); > >First an issue. I am getting a seg fault coming in >DiscreteFunction::interpolate as part of the assemble step. I haven't >figured out why yet, but I'm looking. > >Next, a few questions. >Is there an easier (or cleaner) way to accomplish this? >
Yes, you should be able to assemble a linear form which will contain the reaction forces. For elasticity, plasticity, etc L = -grad(v)*sigma*dx - v*f*dx (f is the body force) Assemble this into a vector, and the vector will contain the reaction forces. Garth >I have a mixed formulation. Is is possible to only assemble the >stiffness matrix for a SubSystem? > >Thanks, >Jake > >_______________________________________________ >DOLFIN-dev mailing list >[email protected] >http://www.fenics.org/mailman/listinfo/dolfin-dev > _______________________________________________ DOLFIN-dev mailing list [email protected] http://www.fenics.org/mailman/listinfo/dolfin-dev
