code: public void sortIndices(SortCoupledArray_F64 sorter ) {
          if( sorter == null )
              sorter = new SortCoupledArray_F64();
  
          sorter.quick(col_idx,numCols+1,nz_rows,nz_values);
          indicesSorted = true;
      }
docs: Sorts the row indices in ascending order.
  @param sorter (Optional) Used to sort rows.  If null a new instance will be declared internally.