petsc-3.14.5 2021-03-03
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# DMDAGetProcessorSubset

Returns a communicator consisting only of the processors in a DMDA that own a particular global x, y, or z grid point (corresponding to a logical plane in a 3D grid or a line in a 2D grid).

### Synopsis

    #include "petscdmda.h"
    PetscErrorCode  DMDAGetProcessorSubset(DM da,DMDirection dir,PetscInt gp,MPI_Comm *comm)

Collective on da

### Input Parameters

| da | - the distributed array
| dir | - Cartesian direction, either DM_X, DM_Y, or DM_Z
| gp | - global grid point number in this direction

### Output Parameters

| comm | - new communicator

### Notes

All processors that share the DMDA must call this with the same gp value

After use, comm should be freed with MPI_Comm_free()

This routine is particularly useful to compute boundary conditions or other application-specific calculations that require manipulating sets of data throughout a logical plane of grid points.

Not supported from Fortran

### Level

advanced

### Location

src/dm/impls/da/dasub.c
Index of all DMDA routines
Table of Contents for all manual pages
Index of all manual pages