On Tue, May 15, 2012 at 2:26 PM, behzad baghapour < behzad.baghapour at gmail.com> wrote:
> OK. The (pseudo) transient technique is a way of globalizing the local > convergent Newton methods which is very helpful when dealing with high > nonlinear problems with a pure initial guess. But the classical line-search > method is to minimize the problem 0.5IIR(x)II^2 which basically does not > see the transient phase. 1. The transient term may give you a direction that is not a descent direction for ||R(x)||^2. For such problems, you _must_ allow ||R(x)|| to _increase_ before you can reach a steady state. 2. ||R(x)||^2 may not be a good objective functional for the line search, especially for non-convex problems. > Then I have to discard this phase in order to match with the structure of > the method. So I am looking forward to find a way to tell the SNES to > consider just the term: dR/dQ when using it to modify the search direction > with its quadratic or cubic model. The line search does not change the search direction, it changes the step length. -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20120515/5b4ca762/attachment.htm>
