    # File lib/graphviz/theory.rb, line 12
        def adjancy_matrix
          matrix = GraphViz::Math::Matrix.new( @graph.node_count, @graph.node_count )

          @graph.each_edge { |e|
            x = @graph.get_node(e.node_one( false )).index
            y = @graph.get_node(e.node_two( false )).index
            matrix[x+1, y+1] = 1
            matrix[y+1, x+1] = 1 if @graph.type == "graph"
          }

          return matrix
        end