From: Roy Stogner <roystgnr@ic...> - 2006-03-27 15:01:45
On Sun, 26 Mar 2006, li pan wrote:
> maybe it's a little stupid. But I have to say it. In
> the Netwon iteration code of ex13, I can't find
> something like Xn+1 = Xn + deltaX.
Oh! I completely misunderstood what you meant by "accumulated
This isn't a stupid question at all, because different codes do it in
different ways. In example 13, I believe what's going on is that the
solution vector itself, *stokes_system.solution, is being used to hold
Xn+1. I think I've just about convinced John that for more tricky
nonlinear problems it's better for the system solution to hold the
difference between deltaX at the last Newton step and deltaX at the
current Newton step, though; the equations usually come out simpler,
and it ends up being easier to program quasiNewton schemes and
John, Ben, am I right about ex13? We probably ought to add comments
to the nonlinear loop explaining as much.