2: /*
3: Code for manipulating distributed regular arrays in parallel.
4: */
6: #include <petsc/private/dmdaimpl.h> 8: /*@C
9: DMDAGetGhostCorners - Returns the global (x,y,z) indices of the lower left
10: corner and size of the local region, including ghost points.
12: Not Collective
14: Input Parameter:
15: . da - the distributed array
17: Output Parameters:
18: + x,y,z - the corner indices (where y and z are optional; these are used
19: for 2D and 3D problems)
20: - m,n,p - widths in the corresponding directions (where n and p are optional;
21: these are used for 2D and 3D problems)
23: Level: beginner
25: Note:
26: The corner information is independent of the number of degrees of
27: freedom per node set with the DMDACreateXX() routine. Thus the x, y, z, and
28: m, n, p can be thought of as coordinates on a logical grid, where each
29: grid point has (potentially) several degrees of freedom.
30: Any of y, z, n, and p can be passed in as NULL if not needed.
32: .seealso: DMDAGetCorners(), DMDACreate1d(), DMDACreate2d(), DMDACreate3d(), DMDAGetOwnershipRanges(), DMStagGetGhostCorners()
34: @*/
35: PetscErrorCodeDMDAGetGhostCorners(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;
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: return(0);
52: }