On Apr 18, 2013, at 11:22 AM, Colin McAuliffe <cjm2176 at columbia.edu> wrote:
> Hello all, > > I am testing out a few linear solvers on a small (1052 by 1052) matrix. Using > unpreconditioned GMRES with -ksp_gmres_restart 10000, GMRES still takes many > times more than 1052 iterations to converge. Shouldn't it be the case that > for a n by n matrix, n iterations of GMRES will give a full factorization of > the matrix? Also run with -ksp_view and make sure that it is actually using that 10,000 restart value. (The restart size will be printed with other information about the solver). You can also run with -ksp_monitor_singular_value this will you give you some idea of the conditioning of the matrix, which likely is huge. Barry > Thanks > > -- > Colin McAuliffe > PhD Candidate > Columbia University > Department of Civil Engineering and Engineering Mechanics
