petsc-3.14.5 2021-03-03
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# DMDACreate2d

Creates an object that will manage the communication of two-dimensional regular array data that is distributed across some processors.

### Synopsis

    #include "petscdmda.h"
    PetscErrorCode  DMDACreate2d(MPI_Comm comm,DMBoundaryType bx,DMBoundaryType by,DMDAStencilType stencil_type,
                                 PetscInt M,PetscInt N,PetscInt m,PetscInt n,PetscInt dof,PetscInt s,const PetscInt lx[],const PetscInt ly[],DM *da)

Collective

### Input Parameters

| comm | - MPI communicator
| bx,by | - type of ghost nodes the array have. Use one of DM_BOUNDARY_NONE, DM_BOUNDARY_GHOSTED, DM_BOUNDARY_PERIODIC.
| stencil_type | - stencil type. Use either DMDA_STENCIL_BOX or DMDA_STENCIL_STAR.
| M,N | - global dimension in each direction of the array
| m,n | - corresponding number of processors in each dimension (or PETSC_DECIDE to have calculated)
| dof | - number of degrees of freedom per node
| s | - stencil width
| lx, ly | - arrays containing the number of nodes in each cell along the x and y coordinates, or NULL. If non-null, these must be of length as m and n, and the corresponding m and n cannot be PETSC_DECIDE. The sum of the lx[] entries must be M, and the sum of the ly[] entries must be N.

### Output Parameter

| da | - the resulting distributed array object

### Options Database Key

| -dm_view | - Calls DMView() at the conclusion of DMDACreate2d()
| -da_grid_x <nx> | - number of grid points in x direction
| -da_grid_y <ny> | - number of grid points in y direction
| -da_processors_x <nx> | - number of processors in x direction
| -da_processors_y <ny> | - number of processors in y direction
| -da_refine_x <rx> | - refinement ratio in x direction
| -da_refine_y <ry> | - refinement ratio in y direction
| -da_refine <n> | - refine the DMDA n times before creating

### Notes

The stencil type DMDA_STENCIL_STAR with width 1 corresponds to the standard 5-pt stencil, while DMDA_STENCIL_BOX with width 1 denotes the standard 9-pt stencil.

The array data itself is NOT stored in the DMDA, it is stored in Vec objects; The appropriate vector objects can be obtained with calls to DMCreateGlobalVector() and DMCreateLocalVector() and calls to VecDuplicate() if more are needed.

You must call DMSetUp() after this call before using this DM.

If you wish to use the options database to change values in the DMDA call DMSetFromOptions() after this call but before DMSetUp().

### See Also

DMDestroy(), DMView(), DMDACreate1d(), DMDACreate3d(), DMGlobalToLocalBegin(), DMDAGetRefinementFactor(),
DMGlobalToLocalEnd(), DMLocalToGlobalBegin(), DMLocalToLocalBegin(), DMLocalToLocalEnd(), DMDASetRefinementFactor(), DMDAGetInfo(), DMCreateGlobalVector(), DMCreateLocalVector(), DMDACreateNaturalVector(), DMLoad(), DMDAGetOwnershipRanges(), DMStagCreate2d()

### Level

beginner

### Location

src/dm/impls/da/da2.c

### Examples

src/dm/tutorials/ex1.c.html
src/dm/tutorials/ex3.c.html
src/dm/tutorials/ex4.c.html
src/dm/tutorials/ex5.c.html
src/dm/tutorials/ex6.c.html
src/dm/tutorials/ex7.c.html
src/dm/tutorials/ex9.c.html
src/dm/tutorials/ex10.c.html
src/dm/tutorials/ex12.c.html
src/dm/tutorials/ex20.c.html
src/dm/tutorials/ex51.c.html
Index of all DMDA routines
Table of Contents for all manual pages
Index of all manual pages