1: /*
  2:   Code for manipulating distributed regular arrays in parallel.
  3: */

  5: #include <petsc/private/dmdaimpl.h>

  7: /*@
  8:   DMDAGetScatter - Gets the global-to-local, and
  9:   local-to-local vector scatter contexts for a `DMDA` distributed array.

 11:   Collective

 13:   Input Parameter:
 14: . da - the `DMDA`

 16:   Output Parameters:
 17: + gtol - global-to-local scatter context (may be `NULL`)
 18: - ltol - local-to-local scatter context (may be `NULL`)

 20:   Level: developer

 22:   Note:
 23:   The output contexts are valid only as long as the input `da` is valid.
 24:   If you delete the `da`, the scatter contexts will become invalid.

 26: .seealso: [](sec_struct), `DM`, `DMDA`, `DMGlobalToLocalBegin()`, `DMGlobalToLocalEnd()`, `DMLocalToGlobalBegin()`
 27: @*/
 28: PetscErrorCode DMDAGetScatter(DM da, VecScatter *gtol, VecScatter *ltol)
 29: {
 30:   DM_DA *dd = (DM_DA *)da->data;

 32:   PetscFunctionBegin;
 34:   if (gtol) *gtol = dd->gtol;
 35:   if (ltol) {
 36:     if (!dd->ltol) PetscCall(DMLocalToLocalCreate_DA(da));
 37:     *ltol = dd->ltol;
 38:   }
 39:   PetscFunctionReturn(PETSC_SUCCESS);
 40: }