MatGetOwnershipRange

For matrices that own values by row, excludes MATELEMENTAL and MATSCALAPACK, returns the range of matrix rows owned by this MPI process.

Synopsis

#include "petscmat.h" 
PetscErrorCode MatGetOwnershipRange(Mat mat, PetscInt *m, PetscInt *n)

Not Collective

Input Parameter

• mat - the matrix

Output Parameters

• m - the global index of the first local row, use NULL to not obtain this value

• n - one more than the global index of the last local row, use NULL to not obtain this value

Notes

If the Mat was obtained from a DM with DMCreateMatrix(), then the range values are determined by the specific DM.

If the Mat was created directly the range values are determined by the local size passed to MatSetSizes() or MatCreateAIJ(). If PETSC_DECIDE was passed as the local size, then the vector uses default values for the range using PetscSplitOwnership().

For certain DM, such as DMDA, it is better to use DM specific routines, such as DMDAGetGhostCorners(), to determine the local values in the matrix.

The high argument is one more than the last element stored locally.

For all matrices it returns the range of matrix rows associated with rows of a vector that would contain the result of a matrix vector product with this matrix. See Matrix Layouts for details on matrix layouts.

See Also

Matrices, Mat, MatGetOwnershipRanges(), MatGetOwnershipRangeColumn(), MatGetOwnershipRangesColumn(), PetscSplitOwnership(), PetscSplitOwnershipBlock(), PetscLayout, MatSetSizes(), MatCreateAIJ(), DMDAGetGhostCorners(), DM

Level

beginner

Location

src/mat/interface/matrix.c

Examples

src/ts/tutorials/ex21.c
src/ts/tutorials/ex44.c
src/ksp/ksp/tutorials/ex15f.F90
src/ts/tutorials/ex74.c
src/ts/tutorials/ex41.c
src/ksp/pc/tutorials/ex3.c
src/ksp/pc/tutorials/ex4.c
src/ts/tutorials/ex17.c
src/ts/tutorials/ex2.c
src/ts/tutorials/ex4.c

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Index of all Mat routines
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Index of all manual pages