Sorry, my mistake. I assumed that the naming would follow PETSc convention and there would be MatGetLocalSubMatrix_something() as there is MatGetLocalSubMatrix_IS() and MatGetLocalSubMatrix_Nest(). Instead MatGetLocalSubMatrix() is hardwired to call MatCreateLocalRef() if the method is not provide for the original matrix.
Now interestingly MatCreateLocalRef() has its own manual page which states: Most will use MatGetLocalSubMatrix(). I am not sure why MatCreateLocalRef() is a public function (that is why it would ever be called directly). Perhaps a note could be added to its manual page indicating why it is public. My inclination would be to make it private and call it MatGetLocalSubMatrix_Basic(). There is harm in having multiple similar public functions unless there is a true need for them. Barry I don't remember the names of anything in PETSc, I only remember the naming conventions, hence when something is nonstandard I tend to get lost. > On May 29, 2019, at 11:13 PM, Jed Brown <j...@jedbrown.org> wrote: > > "Smith, Barry F. via petsc-users" <petsc-users@mcs.anl.gov> writes: > >> This is an interesting idea, but unfortunately not directly compatible >> with libMesh filling up the finite element part of the matrix. Plus it >> appears MatGetLocalSubMatrix() is only implemented for IS and Nest matrices >> :-( > > Maybe I'm missing something, but MatGetLocalSubMatrix *is* implemented > for arbitrary Mats; it returns a view that allows you to set entries > using local submatrix indexing. That was a key feature of the MatNest > work from so many years ago and a paper on which you're coauthor. ;-)
