On Tue, Apr 14, 2015 at 6:15 PM, Gideon Simpson <[email protected]> wrote:
> Other than zeroing things out, is there any substantive difference between > DMCreateLocalVector and DMGetLocalVector? > The Get version caches vectors, so you are not continually creating/destroying Matt > -gideon > > > On Apr 14, 2015, at 7:02 PM, Barry Smith <[email protected]> wrote: > > > > > > When PETSc vectors are created initially they always have 0 everywhere. > So if you use DMCreateLocalVector() it will have zero in all those ghost > places (as well as everywhere else). > > > > But if you use DMGetLocalVector() it returns vectors that maybe dirty > so you need to fill in any locations you want to have a known value with > that known value. Or call VecSet() to clear the entire vector. > > > > Barry > > > >> On Apr 14, 2015, at 5:52 PM, Gideon Simpson <[email protected]> > wrote: > >> > >> If i use the DM_BOUNDARY_GHOSTED flag in the creation of a DMDA array, > are the ghosted values automatically set to zero, or should they be > manually set to zero if that’s the desired ghost value? > >> > >> -gideon > >> > > > > -- 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
