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

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