On Wed, 26 Mar 2014 16:29:11 +0100 "Garth N. Wells" <[email protected]> wrote:
> > On 26 Mar 2014, at 16:26, Jan Blechta <[email protected]> > wrote: > > > On Wed, 26 Mar 2014 16:16:25 +0100 > > Johannes Ring <[email protected]> wrote: > > > >> On Wed, Mar 26, 2014 at 1:39 PM, Jan Blechta > >> <[email protected]> wrote: > >>> As a follow-up of 'Broken PETSc wrappers?' thread on this list, > >>> can anyone reproduce incorrect (orders of magnitude) norm using > >>> superlu_dist on following example? Both in serial and parallel. > >>> Thanks, > >> > >> This is the result I got: > >> > >> Serial: > >> > >> L2 norm mumps 0.611356580181 > >> L2 norm superlu_dist 92.4733890983 > >> > >> Parallel (2 processes): > >> > >> L2 norm mumps 0.611356580181 > >> L2 norm superlu_dist 220.027905995 > >> L2 norm mumps 0.611356580181 > >> L2 norm superlu_dist 220.027905995 > > > > superlu_dist results are obviously wrong. Do we have broken > > installations or is there something wrong with the library? > > > > In the latter case I would suggest switching the default back to > > MUMPS. (Additionally, MUMPS has Cholesky factorization!) What was > > your motivation for switching to superlu_dist, Garth? > > > > MUMPS often fails in parallel with global dofs, and there is no > indication that MUMPS developers are willing to fix bugs. I'm not sure what do you mean by 'MUMPS fails'. I also observe that MUMPS sometimes fails because size of work arrays estimated during symbolic factorization is not sufficient for actual numeric factorization with pivoting. But this is hardly a bug. It can by analyzed simply by increasing verbosity PETScOptions.set('mat_mumps_icntl_4', 3) and fixed by increasing ' work array increase percentage' PETScOptions.set('mat_mumps_icntl_14', 50) # default=25 or decreasing pivoting threshold. I have suspicion that frequent reason for this is using too small partitions (too much processes). (Users should also use Cholesky and PD-Cholesky whenever possible. Numerics is much more better and more things are predictable in analysis phase.) On the other superlu_dist is computing rubbish without any warning for me and Johannes. Can you duplicate? Jan > > Garth > > > Jan > > > >> > >> Johannes > >> _______________________________________________ > >> fenics-support mailing list > >> [email protected] > >> http://fenicsproject.org/mailman/listinfo/fenics-support _______________________________________________ fenics-support mailing list [email protected] http://fenicsproject.org/mailman/listinfo/fenics-support
