A^TA + B?

[Lisandro Dalcin]

Perhaps I missunderstood you, but... Why don't you assemble your
global B matrix from the elemental matrices a^Ta+b ? An then you
should definitelly use as sparse AIJ matrix for this for this and
solve it with an iterative method, but not a dense matrix with lapack.

On 10/26/07, Zhifeng Sheng <z.sheng at ewi.tudelft.nl> wrote:
> Hong Zhang wrote:
> Actually, in this case, I only need to do b = a^T*a + b on local
> matrices, which are very small e.g (12 by 12). The elementary matrices
> will be assembled in the end. Should I use lapack in combination with Petsc?
>


-- 
Lisandro Dalcín
---------------
Centro Internacional de Métodos Computacionales en Ingeniería (CIMEC)
Instituto de Desarrollo Tecnológico para la Industria Química (INTEC)
Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)
PTLC - Güemes 3450, (3000) Santa Fe, Argentina
Tel/Fax: +54-(0)342-451.1594