[Trilinos-Users] blocked problems

[Nico Schlömer]

Hi all,

I would like to extend a (let's say) linear system A by system blocks
E=(A, B; C, D) without disturbing the circles of A (which lives in an
EpetraExt::ModelEvaluator). Given a map mapA for and a map mapE for E,
matrix vector multiplication Y=E*X could certainly be implemented by
first dissecting X, copying over its entries into x, perform y=A*x,
copy its values into Y, and do the rest of the blocks in a similar
fashion. Since all this copying forth and back seems wasteful, I was
wondering if there's a better alternative. In principle, there could
be a vector/operator class stack that sticks a bunch of Epetra_Vectors
and does the right thing for matrix-vector multiplication.
I just looked at EpetraExt::BlockVector and friends which does sound
promising by its name, but I can't quite get the hang of how it's
supposed to be used. May it isn't what I want after all.

Anyone with any experience here?

Cheers,
Nico