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 Dalc?n --------------- Centro Internacional de M?todos Computacionales en Ingenier?a (CIMEC) Instituto de Desarrollo Tecnol?gico para la Industria Qu?mica (INTEC) Consejo Nacional de Investigaciones Cient?ficas y T?cnicas (CONICET) PTLC - G?emes 3450, (3000) Santa Fe, Argentina Tel/Fax: +54-(0)342-451.1594
