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.
