I'm solving the elastic equilibrium equations, which I need to solve many times during a single program run. However, in between calls to the solver, only the RHS of the FEM formulation is changing, i.e. the body forces or Neumann conditions. As in this case the stiffness matrix is constant, I would like to use a direct solver (e.g. umfpack) to calculate the matrix factorization (i.e. setup the solver) only once, an then simply call the solver many times with different body forces. I would really appreciate if some of you could point me in the right direction, or provide me with a couple of lines of code showing how this can be (more or less) achieved with this really nice module.

Thank very much!