On Thu, Sep 25, 2008 at 03:11:27PM +0100, Garth N. Wells wrote: > > > Anders Logg wrote: > > On Thu, Sep 25, 2008 at 12:41:33PM +0100, Garth N. Wells wrote: > >> Nuno David Lopes wrote: > >>> Is there a simple way of setting an initial guess for an Iterative > >>> LinearSolver? > >>> In Umfpack and PETSc the default initial guess is the zero vector right? > >> At the moment, yes (note the UMFPACK is an LU solver, so an initial > >> guess doesn't do anything). > >> > >> It's very simple, and I've been meaning to add an option for using an > >> initial guess. It's also useful for Newton solvers. I'll add something > >> in the next few days. > >> > >> Garth > > > > It would be natural to let the x argument always be the initial > > guess. I thought we already did this. > > > > Would it be enough to make sure that Vector::init() does not reset the > > values to zero? > > > > Yes. > > The danger is if someone sends an uninitialised vector to the solver. > > Garth
We can just put something like this in the init() functions:
if (x && size() == N)
return;
I think we had this a while back but at some point VecZeroEntries was
inserted.
--
Anders
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