[petsc-users] kronecker products

[Jed Brown]

On Thu, Nov 4, 2010 at 10:18, Benjamin Sanderse <B.Sanderse at cwi.nl> wrote:

> 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.
>

I'm curious about the structure of these kronecker products.  For example,
you may have

K = A \otimes B

Is either one of A or B dense?  Are they both large and distributed, or is
one much smaller than the other?  If they are both distributed, what
distribution do you want the vector to have?

A different question is, what problem are you solving?  E.g. if this is a
Galerkin method for stochastic PDE, it gives us some idea about the
structure, and the natural follow-up question is what is the size of the
(reduced how?) stochastic space, and do the stochastic basis functions have
local or global support.

Jed
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