Date: 2013-07-02T14:44:55+00:00

Actual source code: daghost.c
petsc-3.4.2 2013-07-02

      2: /*
      3:   Code for manipulating distributed regular arrays in parallel.
      4: */

      6: #include <petsc-private/dmdaimpl.h>    /*I   "petscdmda.h"   I*/

     10: /*@
     11:    DMDAGetGhostCorners - Returns the global (x,y,z) indices of the lower left
     12:    corner of the local region, including ghost points.

     14:    Not Collective

     16:    Input Parameter:
     17: .  da - the distributed array

     19:    Output Parameters:
     20: +  x,y,z - the corner indices (where y and z are optional; these are used
     21:            for 2D and 3D problems)
     22: -  m,n,p - widths in the corresponding directions (where n and p are optional;
     23:            these are used for 2D and 3D problems)

     25:    Level: beginner

     27:    Note:
     28:    The corner information is independent of the number of degrees of
     29:    freedom per node set with the DMDACreateXX() routine. Thus the x, y, z, and
     30:    m, n, p can be thought of as coordinates on a logical grid, where each
     31:    grid point has (potentially) several degrees of freedom.
     32:    Any of y, z, n, and p can be passed in as NULL if not needed.

     34: .keywords: distributed array, get, ghost, corners, nodes, local indices

     36: .seealso: DMDAGetCorners(), DMDACreate1d(), DMDACreate2d(), DMDACreate3d(), DMDAGetOwnershipRanges()

     38: @*/
     39: PetscErrorCode  DMDAGetGhostCorners(DM da,PetscInt *x,PetscInt *y,PetscInt *z,PetscInt *m,PetscInt *n,PetscInt *p)
     40: {
     41:   PetscInt w;
     42:   DM_DA    *dd = (DM_DA*)da->data;

     46:   /* since the xs, xe ... have all been multiplied by the number of degrees
     47:      of freedom per cell, w = dd->w, we divide that out before returning.*/
     48:   w = dd->w;
     49:   if (x) *x = dd->Xs/w + dd->xo; if (m) *m = (dd->Xe - dd->Xs)/w;
     50:   if (y) *y = dd->Ys   + dd->yo; if (n) *n = (dd->Ye - dd->Ys);
     51:   if (z) *z = dd->Zs   + dd->zo; if (p) *p = (dd->Ze - dd->Zs);
     52:   return(0);
     53: }