Actual source code: plexindices.c
petsc-3.10.5 2019-03-28
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      1:  #include <petsc/private/dmpleximpl.h>

      3: /*@
      4:   DMPlexCreateClosureIndex - Calculate an index for the given PetscSection for the closure operation on the DM

      6:   Not collective

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

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

     15:   Level: intermediate

     17: .seealso DMPlexVecGetClosure(), DMPlexVecRestoreClosure(), DMPlexVecSetClosure(), DMPlexMatSetClosure()
     18: @*/
     19: PetscErrorCode DMPlexCreateClosureIndex(DM dm, PetscSection section)
     20: {
     21:   PetscSection   closureSection;
     22:   IS             closureIS;
     23:   PetscInt      *clPoints;
     24:   PetscInt       pStart, pEnd, sStart, sEnd, point, clSize;

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

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

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