On Sat, Apr 24, 2010 at 03:35:33PM +0200, Andre Massing wrote: > > > Anders Logg wrote: > >On Fri, Apr 23, 2010 at 10:44:19AM +0100, Garth N. Wells wrote: > >> > >>Anders Logg wrote: > >>>On Fri, Apr 23, 2010 at 09:34:16AM +0100, Garth N. Wells wrote: > >>>>This sounds very PETSc-speecific. Should it be a parameter of > >>>>PETScMatrix only? > >>>> > >>>>Garth > >>>Yes, perhaps. I find it a bit strange that MatZeroRows breaks for > >>>rows without elements. > >>> > >>Send a PETSc bug report? > > > >Yes, that might be the best option. > > > >>A solution would be to check the number of row entries, if possible. > > > >I also though of that but didn't find a fast way to check it. Perhaps > >I've overlooked some PETSc function that does this? > > I checked the PETSc doc and the DOLFIN code and and setting the > parameter in dolfin/la/PETScMatrix.cpp > > MatSetOption(*A, MAT_KEEP_ZEROED_ROWS, PETSC_TRUE); > > causes to the MatZeroRowIS function not to the change the nonzero structure: > http://www.mcs.anl.gov/petsc/petsc-as/snapshots/petsc-current/docs/manualpages/Mat/MatSetOption.html#MatSetOption > and > http://www.mcs.anl.gov/petsc/petsc-as/snapshots/petsc-current/docs/manualpages/Mat/MatZeroRowsIS.html#MatZeroRowsIS > > and seems therefore (in our case) to throw an error if you want to > add a nonzero value to a zero diagonal entry. > > Just tested it here and it went fine without setting use_ident=false. > What is the reason for setting this option?
I don't remember. We've had it there for a long time. Does anyone know why it's there? -- Anders
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