DMLocatePoints#

Locate the points in v in the mesh and return a PetscSF of the containing cells

Synopsis#

#include "petscdm.h"          
PetscErrorCode DMLocatePoints(DM dm, Vec v, DMPointLocationType ltype, PetscSF *cellSF)

Collective

Input Parameters#

dm - The DM
ltype - The type of point location, e.g. DM_POINTLOCATION_NONE or DM_POINTLOCATION_NEAREST

Input/Output Parameters#

v - The Vec of points, on output contains the nearest mesh points to the given points if DM_POINTLOCATION_NEAREST is used
cellSF - Points to either NULL, or a PetscSF with guesses for which cells contain each point; on output, the PetscSF containing the ranks and local indices of the containing points

Notes#

To do a search of the local cells of the mesh, v should have PETSC_COMM_SELF as its communicator. To do a search of all the cells in the distributed mesh, v should have the same communicator as dm.

Points will only be located in owned cells, not overlap cells arising from DMPlexDistribute() or other overlapping distributions.

If *cellSF is NULL on input, a PetscSF will be created. If *cellSF is not NULL on input, it should point to an existing PetscSF, whose graph will be used as initial guesses.

An array that maps each point to its containing cell can be obtained with

    const PetscSFNode *cells;
    PetscInt           nFound;
    const PetscInt    *found;

    PetscSFGetGraph(cellSF,NULL,&nFound,&found,&cells);

Where cells[i].rank is the rank of the process owning the cell containing point found[i] (or i if found == NULL), and cells[i].index is the index of the cell in its rank’s local numbering. This rank is in the communicator for v, so if v is on PETSC_COMM_SELF then the rank will always be 0.