retrieves values from certain locations in a matrix using the local numbering of the indices defined previously by MatSetLocalToGlobalMapping()
PetscErrorCode MatGetValuesLocal(Mat mat,PetscInt nrow,const PetscInt irow,PetscInt ncol,const PetscInt icol,PetscScalar y)
|mat ||- the matrix
|nrow, irow ||- number of rows and their local indices
|ncol, icol ||- number of columns and their local indices
|y ||- a logically two-dimensional array of values
If you create the matrix yourself (that is not with a call to DMCreateMatrix()) then you MUST call MatSetLocalToGlobalMapping() before using this routine.
This routine can only return values that are owned by the requesting MPI rank. That is, for standard matrix formats, rows that, in the global numbering,
are greater than or equal to restart and less than rend where restart and rend are obtainable from MatGetOwnershipRange(mat,&rstart,&rend). One can
determine if the resulting global row associated with the local row r is owned by the requesting MPI rank by applying the ISLocalToGlobalMapping set
This is labelled with C so does not automatically generate Fortran stubs and interfaces
because it requires multiple Fortran interfaces depending on which arguments are scalar or arrays.
MatAssemblyBegin(), MatAssemblyEnd(), MatSetValues(), MatSetLocalToGlobalMapping(),
Index of all Mat routines
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Index of all manual pages