Actual source code: spnd.c

 2:  #include petscmat.h
 3:  #include src/mat/order/order.h

  6: /*
  7:     MatOrdering_ND - Find the nested dissection ordering of a given matrix.
  8: */
 11: PetscErrorCode MatOrdering_ND(Mat mat,const MatOrderingType type,IS *row,IS *col)
 12: {
 14:   PetscInt       i, *mask,*xls,*ls,nrow,*ia,*ja,*perm;
 15:   PetscTruth     done;

 18:   MatGetRowIJ(mat,1,PETSC_TRUE,&nrow,&ia,&ja,&done);
 19:   if (!done) SETERRQ1(PETSC_ERR_SUP,"Cannot get rows for matrix type %s",((PetscObject)mat)->type_name);

 21:   PetscMalloc((4*nrow +1) * sizeof(PetscInt),&mask);
 22:   perm = mask + nrow;
 23:   xls  = perm + nrow;
 24:   ls   = xls  + nrow + 1;

 26:   SPARSEPACKgennd(&nrow,ia,ja,mask,perm,xls,ls);
 27:   MatRestoreRowIJ(mat,1,PETSC_TRUE,&nrow,&ia,&ja,&done);

 29:   /* shift because Sparsepack indices start at one */
 30:   for (i=0; i<nrow; i++) perm[i]--;

 32:   ISCreateGeneral(PETSC_COMM_SELF,nrow,perm,row);
 33:   ISCreateGeneral(PETSC_COMM_SELF,nrow,perm,col);
 34:   PetscFree(mask);

 36:   return(0);
 37: }