Actual source code: spnd.c

      1: #define PETSCMAT_DLL

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

      7: /*
      8:     MatOrdering_ND - Find the nested dissection ordering of a given matrix.
      9: */
     12: PetscErrorCode PETSCMAT_DLLEXPORT MatOrdering_ND(Mat mat,const MatOrderingType type,IS *row,IS *col)
     13: {
     15:   PetscInt       i, *mask,*xls,*ls,nrow,*ia,*ja,*perm;
     16:   PetscTruth     done;

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

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

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

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

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

     37:   return(0);
     38: }