> On Dec 16, 2016, at 8:17 PM, Massoud Rezavand <[email protected]> wrote: > > Dear PETSc team, > > Sorry if my question is more related to math. > Using PETSc, how important is the structure of the matrix A for performance? > I mean mainly the diagonal and off-diagonal parts. > > For example, solving with a matrix which is dense in diagonal part and sparse > in off-diagonal part is faster than with a matrix in which the non-zeros are > distributed randomly?
Yes, loosely speaking this is true. More technically there is a term "diagonally dominate", or block diagonally dominate, for those matrices generally iterative methods perform better. Barry > > Thanks in advance. > > Massoud
