On Thu, Sep 4, 2014 at 12:28 PM, Jed Brown <[email protected]> wrote:
> Miguel Angel Salazar de Troya <[email protected]> writes: > > > Dear all > > > > SNES uses internally a KSP to solve the linear system of equations right? > > Now the case that we had a linear system of equations that we are solving > > with SNES, how could we set the initial estimation for the KSP? If we > just > > included the option -ksp_initial_guess_nonzero, the KSP will grab the > > vector X we passed to the SNES? > > You definitely don't want this for Newton-type methods. If you have a > nonzero guess for the solution of the linear system, you should have > evaluated the Jacobian at that point. A zero initial guess is optimal > for Newton-type methods. > Notice that Newton is solving for the correction, not the solution itself. Matt -- What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead. -- Norbert Wiener
