Actual source code: spnd.c
2: #include <petscmat.h>
3: #include <petsc/private/matorderimpl.h>
5: /*
6: MatGetOrdering_ND - Find the nested dissection ordering of a given matrix.
7: */
8: PETSC_INTERN PetscErrorCode MatGetOrdering_ND(Mat mat,MatOrderingType type,IS *row,IS *col)
9: {
11: PetscInt i, *mask,*xls,*ls,nrow,*perm;
12: const PetscInt *ia,*ja;
13: PetscBool done;
14: Mat B = NULL;
17: MatGetRowIJ(mat,1,PETSC_TRUE,PETSC_TRUE,&nrow,&ia,&ja,&done);
18: if (!done) {
19: MatConvert(mat,MATSEQAIJ,MAT_INITIAL_MATRIX,&B);
20: MatGetRowIJ(B,1,PETSC_TRUE,PETSC_TRUE,&nrow,&ia,&ja,&done);
21: }
23: PetscMalloc4(nrow,&mask,nrow,&perm,nrow+1,&xls,nrow,&ls);
24: SPARSEPACKgennd(&nrow,ia,ja,mask,perm,xls,ls);
25: if (B) {
26: MatRestoreRowIJ(B,1,PETSC_TRUE,PETSC_TRUE,NULL,&ia,&ja,&done);
27: MatDestroy(&B);
28: } else {
29: MatRestoreRowIJ(mat,1,PETSC_TRUE,PETSC_TRUE,NULL,&ia,&ja,&done);
30: }
32: /* shift because Sparsepack indices start at one */
33: for (i=0; i<nrow; i++) perm[i]--;
35: ISCreateGeneral(PETSC_COMM_SELF,nrow,perm,PETSC_COPY_VALUES,row);
36: ISCreateGeneral(PETSC_COMM_SELF,nrow,perm,PETSC_COPY_VALUES,col);
37: PetscFree4(mask,perm,xls,ls);
38: return(0);
39: }