[petsc-users] kronecker products

[Benjamin Sanderse]

I am not sure if I understand you correctly. During initialization, several matrices are formed by kronecker products, and the resulting matrices have the size of the number of unknowns; i.e. if n is the number of unknowns then the matrices are n x n, although they typically have only a*n nonzero elements, with a around 10-20.
After initialization a time loop starts in which these matrices are used for matrix-vector products (e.g. to calculate a first or second derivative) and things like CG or Multigrid are used to solve a number of matrix-vector equations (e.g. a Poisson equation for the pressure). This is repeated each time step.



----- Original Message -----
From: "Jed Brown" <jed at 59A2.org>
To: "PETSc users list" <petsc-users at mcs.anl.gov>
Sent: Thursday, November 4, 2010 4:03:15 PM
Subject: Re: [petsc-users] kronecker products

On Thu, Nov 4, 2010 at 09:58, Benjamin Sanderse <B.Sanderse at cwi.nl> wrote:

> Some matrices are just used to compute matrix-vector products, and some
> have to be solved for. That's basically it.
> The matrices are really very sparse; on the order of 10-20 diagonals
> (typically independent of problem size).
> As far as I know, reordering is hardly necessary, because I am using a
> structured grid.
>

What are the relative sizes of each piece?  How are you producing these
matrices?  How do you want the vector distributed?

Jed