On Thu, Mar 30, 2017 at 2:17 PM, Justin Chang <[email protected]> wrote:
> Hi all, > > Just a general conceptual question: say I am tinkering around with SNES > ex48.c and am running the program with these options: > > mpirun -n $NPROCS -pc_type mg -M $XSEED -N $YSEED -P $ZSEED -thi_mat_type > baij -da_refine $DAREFINE -pc_mg_levels $MGLEVELS > > I am not too familiar with mg, but it seems to me there is a very strong > correlation between $MGLEVELS and $DAREFINE as well as perhaps even the > initial coarse grid size (provided by $X/YZSEED). > > Is there a rule of thumb on how these parameters should be? I am guessing > it probably is also hardware/architectural dependent? > You cannot refine further than 1 grid point in any direction. Moreover, DMDA has some problems with MG on grids without an odd number of vertices I think. Matt > Thanks, > Justin > -- What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead. -- Norbert Wiener
