VecGetOwnershipRange — PETSc 3.23.0 documentation

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# VecGetOwnershipRange

Returns the range of indices owned by this process. The vector is laid out with the first `n1` elements on the first processor, next `n2` elements on the second, etc. For certain parallel layouts this range may not be well defined.

## Synopsis

    #include "petscvec.h"
    PetscErrorCode VecGetOwnershipRange(Vec x, PetscInt *low, PetscInt *high)

Not Collective

## Input Parameter

- x - the vector

## Output Parameters

- low - the first local element, pass in `NULL` if not interested

- high - one more than the last local element, pass in `NULL` if not interested

## Notes

If the `Vec` was obtained from a `DM` with `DMCreateGlobalVector()`, then the range values are determined by the specific `DM`.

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

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

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

## See Also

Vectors and Parallel Data, `Vec`, `MatGetOwnershipRange()`, `MatGetOwnershipRanges()`, `VecGetOwnershipRanges()`, `PetscSplitOwnership()`, `VecSetSizes()`, `VecCreateMPI()`, `PetscLayout`, `DMDAGetGhostCorners()`, `DM`

## Level

beginner

## Location

src/vec/vec/interface/vector.c

## Examples

src/dm/tutorials/ex22.c
src/ksp/ksp/tutorials/ex73.c
src/ksp/ksp/tutorials/ex74.c
src/ksp/ksp/tutorials/ex10.c
src/ksp/ksp/tutorials/ex3.c
src/ksp/ksp/tutorials/ex9.c
src/ksp/ksp/tutorials/ex23.c
src/ksp/ksp/tutorials/ex49.c
src/ksp/ksp/tutorials/ex5.c
src/dm/tutorials/ex6.c

Index of all Vec routines
Table of Contents for all manual pages
Index of all manual pages