1: #include <petsc/private/dmpleximpl.h>   /*I      "petscdmplex.h"   I*/

  5: /*@
  6:   DMPlexCreateClosureIndex - Calculate an index for the given PetscSection for the closure operation on the DM

  8:   Not collective

 10:   Input Parameters:
 11: + dm - The DM
 12: - section - The section describing the layout in v, or NULL to use the default section

 14:   Note:
 15:   This should greatly improve the performance of the closure operations, at the cost of additional memory.

 17:   Level: intermediate

 19: .seealso DMPlexVecGetClosure(), DMPlexVecRestoreClosure(), DMPlexVecSetClosure(), DMPlexMatSetClosure()
 20: @*/
 21: PetscErrorCode DMPlexCreateClosureIndex(DM dm, PetscSection section)
 22: {
 23:   PetscSection   closureSection;
 24:   IS             closureIS;
 25:   PetscInt      *clPoints;
 26:   PetscInt       pStart, pEnd, sStart, sEnd, point, clSize;

 31:   if (!section) {DMGetDefaultSection(dm, &section);}
 33:   PetscSectionGetChart(section, &sStart, &sEnd);
 34:   DMPlexGetChart(dm, &pStart, &pEnd);
 35:   PetscSectionCreate(PetscObjectComm((PetscObject) section), &closureSection);
 36:   PetscSectionSetChart(closureSection, pStart, pEnd);
 37:   for (point = pStart; point < pEnd; ++point) {
 38:     PetscInt *points = NULL, numPoints, p, dof, cldof = 0;

 40:     DMPlexGetTransitiveClosure(dm, point, PETSC_TRUE, &numPoints, &points);
 41:     for (p = 0; p < numPoints*2; p += 2) {
 42:       if ((points[p] >= sStart) && (points[p] < sEnd)) {
 43:         PetscSectionGetDof(section, points[p], &dof);
 44:         if (dof) cldof += 2;
 45:       }
 46:     }
 47:     DMPlexRestoreTransitiveClosure(dm, point, PETSC_TRUE, &numPoints, &points);
 48:     PetscSectionSetDof(closureSection, point, cldof);
 49:   }
 50:   PetscSectionSetUp(closureSection);
 51:   PetscSectionGetStorageSize(closureSection, &clSize);
 52:   PetscMalloc1(clSize, &clPoints);
 53:   for (point = pStart; point < pEnd; ++point) {
 54:     PetscInt *points = NULL, numPoints, p, q, dof, cldof, cloff;

 56:     PetscSectionGetDof(closureSection, point, &cldof);
 57:     PetscSectionGetOffset(closureSection, point, &cloff);
 58:     DMPlexGetTransitiveClosure(dm, point, PETSC_TRUE, &numPoints, &points);
 59:     for (p = 0, q = 0; p < numPoints*2; p += 2) {
 60:       if ((points[p] >= sStart) && (points[p] < sEnd)) {
 61:         PetscSectionGetDof(section, points[p], &dof);
 62:         if (dof) {
 63:           clPoints[cloff+q*2]   = points[p];
 64:           clPoints[cloff+q*2+1] = points[p+1];
 65:           ++q;
 66:         }
 67:       }
 68:     }
 69:     DMPlexRestoreTransitiveClosure(dm, point, PETSC_TRUE, &numPoints, &points);
 70:     if (q*2 != cldof) SETERRQ2(PetscObjectComm((PetscObject) dm), PETSC_ERR_PLIB, "Invalid size for closure %d should be %d", q*2, cldof);
 71:   }
 72:   ISCreateGeneral(PETSC_COMM_SELF, clSize, clPoints, PETSC_OWN_POINTER, &closureIS);
 73:   PetscSectionSetClosureIndex(section, (PetscObject) dm, closureSection, closureIS);
 74:   return(0);
 75: }