Actual source code: sprcm.c
petsc-3.9.4 2018-09-11
2: #include <petscmat.h>
3: #include <petsc/private/matorderimpl.h>
5: /*
6: MatGetOrdering_RCM - Find the Reverse Cuthill-McKee ordering of a given matrix.
7: */
8: PETSC_INTERN PetscErrorCode MatGetOrdering_RCM(Mat mat,MatOrderingType type,IS *row,IS *col)
9: {
11: PetscInt i,*mask,*xls,nrow,*perm;
12: const PetscInt *ia,*ja;
13: PetscBool done;
16: MatGetRowIJ(mat,1,PETSC_TRUE,PETSC_TRUE,&nrow,&ia,&ja,&done);
17: if (!done) SETERRQ(PetscObjectComm((PetscObject)mat),PETSC_ERR_SUP,"Cannot get rows for matrix");
19: PetscMalloc3(nrow,&mask,nrow,&perm,2*nrow,&xls);
20: SPARSEPACKgenrcm(&nrow,ia,ja,perm,mask,xls);
21: MatRestoreRowIJ(mat,1,PETSC_TRUE,PETSC_TRUE,NULL,&ia,&ja,&done);
23: /* shift because Sparsepack indices start at one */
24: for (i=0; i<nrow; i++) perm[i]--;
25: ISCreateGeneral(PETSC_COMM_SELF,nrow,perm,PETSC_COPY_VALUES,row);
26: ISCreateGeneral(PETSC_COMM_SELF,nrow,perm,PETSC_COPY_VALUES,col);
27: PetscFree3(mask,perm,xls);
28: return(0);
29: }