# File lib/graphviz/math/matrix.rb, line 83
      def to_s
        size = bigger
        out = ""
        @line.times do |line|
          out << "["
          @column.times do |column|
            out << sprintf(" %1$*2$s", @matrix[line][column].to_s, size)
          end
          out << "]\n"
        end
        return out
      end