/*
MatGetOrdering_RCM - Find the Reverse Cuthill-McKee ordering of a given matrix.
*/
PETSC_INTERN PetscErrorCode MatGetOrdering_RCM(Mat mat,MatOrderingType type,IS *row,IS *col)
{
PetscErrorCode ierr;
PetscInt i,*mask,*xls,nrow,*perm;
const PetscInt *ia,*ja;
PetscBool done;
PetscFunctionBegin;
ierr = MatGetRowIJ(mat,1,PETSC_TRUE,PETSC_TRUE,&nrow,&ia,&ja,&done);
CHKERRQ(ierr);
if (!done) SETERRQ(PetscObjectComm((PetscObject)mat),PETSC_ERR_SUP,"Cannot get rows for matrix");
ierr = PetscMalloc3(nrow,&mask,nrow,&perm,2*nrow,&xls);
CHKERRQ(ierr);
SPARSEPACKgenrcm(&nrow,ia,ja,perm,mask,xls);
ierr = MatRestoreRowIJ(mat,1,PETSC_TRUE,PETSC_TRUE,NULL,&ia,&ja,&done);
CHKERRQ(ierr);
/* shift because Sparsepack indices start at one */
for (i=0; i<nrow; i++) perm[i]--;
ierr = ISCreateGeneral(PETSC_COMM_SELF,nrow,perm,PETSC_COPY_VALUES,row);
CHKERRQ(ierr);
ierr = ISCreateGeneral(PETSC_COMM_SELF,nrow,perm,PETSC_COPY_VALUES,col);
CHKERRQ(ierr);
ierr = PetscFree3(mask,perm,xls);
CHKERRQ(ierr);
PetscFunctionReturn(0);
}
EXTERN_C_BEGIN
/*
MatOrdering_RCM - Find the Reverse Cuthill-McKee ordering of a given matrix.
*/
#undef __FUNCT__
#define __FUNCT__ "MatOrdering_RCM"
PetscErrorCode PETSCMAT_DLLEXPORT MatOrdering_RCM(Mat mat,const MatOrderingType type,IS *row,IS *col)
{
PetscErrorCode ierr;
PetscInt i,*mask,*xls,nrow,*ia,*ja,*perm;
PetscTruth done;
PetscFunctionBegin;
ierr = MatGetRowIJ(mat,1,PETSC_TRUE,PETSC_TRUE,&nrow,&ia,&ja,&done);CHKERRQ(ierr);
if (!done) SETERRQ(PETSC_ERR_SUP,"Cannot get rows for matrix");
ierr = PetscMalloc3(nrow,PetscInt,&mask,nrow,PetscInt,&perm,2*nrow,PetscInt,&xls);CHKERRQ(ierr);
SPARSEPACKgenrcm(&nrow,ia,ja,perm,mask,xls);
ierr = MatRestoreRowIJ(mat,1,PETSC_TRUE,PETSC_TRUE,&nrow,&ia,&ja,&done);CHKERRQ(ierr);
/* shift because Sparsepack indices start at one */
for (i=0; i<nrow; i++) perm[i]--;
ierr = ISCreateGeneral(PETSC_COMM_SELF,nrow,perm,row);CHKERRQ(ierr);
ierr = ISCreateGeneral(PETSC_COMM_SELF,nrow,perm,col);CHKERRQ(ierr);
ierr = PetscFree3(mask,perm,xls);CHKERRQ(ierr);
PetscFunctionReturn(0);
}
/*@
DMPlexGetOrdering - Calculate a reordering of the mesh
Collective on DM
Input Parameter:
+ dm - The DMPlex object
. otype - type of reordering, one of the following:
$ MATORDERINGNATURAL - Natural
$ MATORDERINGND - Nested Dissection
$ MATORDERING1WD - One-way Dissection
$ MATORDERINGRCM - Reverse Cuthill-McKee
$ MATORDERINGQMD - Quotient Minimum Degree
- label - [Optional] Label used to segregate ordering into sets, or NULL
Output Parameter:
. perm - The point permutation as an IS, perm[old point number] = new point number
Note: The label is used to group sets of points together by label value. This makes it easy to reorder a mesh which
has different types of cells, and then loop over each set of reordered cells for assembly.
Level: intermediate
.keywords: mesh
.seealso: MatGetOrdering()
@*/
PetscErrorCode DMPlexGetOrdering(DM dm, MatOrderingType otype, DMLabel label, IS *perm)
{
PetscInt numCells = 0;
PetscInt *start = NULL, *adjacency = NULL, *cperm, *clperm, *invclperm, *mask, *xls, pStart, pEnd, c, i;
PetscErrorCode ierr;
PetscFunctionBegin;
PetscValidHeaderSpecific(dm, DM_CLASSID, 1);
PetscValidPointer(perm, 3);
ierr = DMPlexCreateNeighborCSR(dm, 0, &numCells, &start, &adjacency);CHKERRQ(ierr);
ierr = PetscMalloc3(numCells,&cperm,numCells,&mask,numCells*2,&xls);CHKERRQ(ierr);
if (numCells) {
/* Shift for Fortran numbering */
for (i = 0; i < start[numCells]; ++i) ++adjacency[i];
for (i = 0; i <= numCells; ++i) ++start[i];
ierr = SPARSEPACKgenrcm(&numCells, start, adjacency, cperm, mask, xls);CHKERRQ(ierr);
}
ierr = PetscFree(start);CHKERRQ(ierr);
ierr = PetscFree(adjacency);CHKERRQ(ierr);
/* Shift for Fortran numbering */
for (c = 0; c < numCells; ++c) --cperm[c];
/* Segregate */
if (label) {
IS valueIS;
const PetscInt *values;
PetscInt numValues, numPoints = 0;
PetscInt *sperm, *vsize, *voff, v;
ierr = DMLabelGetValueIS(label, &valueIS);CHKERRQ(ierr);
ierr = ISSort(valueIS);CHKERRQ(ierr);
ierr = ISGetLocalSize(valueIS, &numValues);CHKERRQ(ierr);
ierr = ISGetIndices(valueIS, &values);CHKERRQ(ierr);
ierr = PetscCalloc3(numCells,&sperm,numValues,&vsize,numValues+1,&voff);CHKERRQ(ierr);
for (v = 0; v < numValues; ++v) {
ierr = DMLabelGetStratumSize(label, values[v], &vsize[v]);CHKERRQ(ierr);
if (v < numValues-1) voff[v+2] += vsize[v] + voff[v+1];
numPoints += vsize[v];
}
if (numPoints != numCells) SETERRQ2(PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Label only covers %D cells < %D total", numPoints, numCells);
for (c = 0; c < numCells; ++c) {
const PetscInt oldc = cperm[c];
PetscInt val, vloc;
ierr = DMLabelGetValue(label, oldc, &val);CHKERRQ(ierr);
if (val == -1) SETERRQ1(PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Cell %D not present in label", oldc);
ierr = PetscFindInt(val, numValues, values, &vloc);CHKERRQ(ierr);
if (vloc < 0) SETERRQ1(PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Value %D not present label", val);
sperm[voff[vloc+1]++] = oldc;
}
for (v = 0; v < numValues; ++v) {
if (voff[v+1] - voff[v] != vsize[v]) SETERRQ3(PETSC_COMM_SELF, PETSC_ERR_PLIB, "Number of %D values found is %D != %D", values[v], voff[v+1] - voff[v], vsize[v]);
}
ierr = ISRestoreIndices(valueIS, &values);CHKERRQ(ierr);
ierr = ISDestroy(&valueIS);CHKERRQ(ierr);
ierr = PetscMemcpy(cperm, sperm, numCells * sizeof(PetscInt));CHKERRQ(ierr);
ierr = PetscFree3(sperm, vsize, voff);CHKERRQ(ierr);
}
/* Construct closure */
ierr = DMPlexCreateOrderingClosure_Static(dm, numCells, cperm, &clperm, &invclperm);CHKERRQ(ierr);
ierr = PetscFree3(cperm,mask,xls);CHKERRQ(ierr);
ierr = PetscFree(clperm);CHKERRQ(ierr);
/* Invert permutation */
ierr = DMPlexGetChart(dm, &pStart, &pEnd);CHKERRQ(ierr);
ierr = ISCreateGeneral(PetscObjectComm((PetscObject) dm), pEnd-pStart, invclperm, PETSC_OWN_POINTER, perm);CHKERRQ(ierr);
PetscFunctionReturn(0);
}
