1 /* 2 Code for manipulating distributed regular arrays in parallel. 3 */ 4 5 #include <petsc/private/dmdaimpl.h> /*I "petscdmda.h" I*/ 6 7 /*@C 8 DMDAGetGhostCorners - Returns the global (x,y,z) indices of the lower left 9 corner and size of the local region, including ghost points. 10 11 Not Collective 12 13 Input Parameter: 14 . da - the distributed array 15 16 Output Parameters: 17 + x - the corner index for the first dimension 18 . y - the corner index for the second dimension (only used in 2D and 3D problems) 19 . z - the corner index for the third dimension (only used in 3D problems) 20 . m - the width in the first dimension 21 . n - the width in the second dimension (only used in 2D and 3D problems) 22 - p - the width in the third dimension (only used in 3D problems) 23 24 Level: beginner 25 26 Note: 27 The corner information is independent of the number of degrees of 28 freedom per node set with the `DMDACreateXX()` routine. Thus the `x`, `y`, `z`, and 29 `m`, `n`, `p` can be thought of as coordinates on a logical grid, where each 30 grid point has (potentially) several degrees of freedom. 31 Any of `y`, `z`, `n`, and `p` can be passed in as `NULL` if not needed. 32 33 .seealso: [](sec_struct), `DM`, `DMDA`, `DMDAGetCorners()`, `DMDACreate1d()`, `DMDACreate2d()`, `DMDACreate3d()`, `DMDAGetOwnershipRanges()`, `DMStagGetGhostCorners()` 34 @*/ 35 PetscErrorCode DMDAGetGhostCorners(DM da, PetscInt *x, PetscInt *y, PetscInt *z, PetscInt *m, PetscInt *n, PetscInt *p) 36 { 37 PetscInt w; 38 DM_DA *dd = (DM_DA *)da->data; 39 40 PetscFunctionBegin; 41 PetscValidHeaderSpecificType(da, DM_CLASSID, 1, DMDA); 42 /* since the xs, xe ... have all been multiplied by the number of degrees 43 of freedom per cell, w = dd->w, we divide that out before returning.*/ 44 w = dd->w; 45 if (x) *x = dd->Xs / w + dd->xo; 46 if (y) *y = dd->Ys + dd->yo; 47 if (z) *z = dd->Zs + dd->zo; 48 if (m) *m = (dd->Xe - dd->Xs) / w; 49 if (n) *n = (dd->Ye - dd->Ys); 50 if (p) *p = (dd->Ze - dd->Zs); 51 PetscFunctionReturn(PETSC_SUCCESS); 52 } 53