So other than the minor point of it zeroing out the data, is there any conceivable reason to use Create/Destroy over Get/Restore?
-gideon > On Apr 14, 2015, at 7:16 PM, Matthew Knepley <knep...@gmail.com> wrote: > > On Tue, Apr 14, 2015 at 6:15 PM, Gideon Simpson <gideon.simp...@gmail.com > <mailto:gideon.simp...@gmail.com>> 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 <bsm...@mcs.anl.gov > > <mailto:bsm...@mcs.anl.gov>> 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 <gideon.simp...@gmail.com > >> <mailto:gideon.simp...@gmail.com>> 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
