# File lib/eymiha/units/units_hash.rb, line 97
    def reduce
      puts "UnitsHash:reduce #{to_s}" if @@debug
      factor = 1.0
      new_unit = UnitsHash.new
      each do |unit,power|
        puts "  #{unit} #{power}" if @@debug
        factor *= unit.equals.numeric**power
        puts "  #{factor}" if @@debug
        new_unit.merge!(unit.equals,power)
      end
      factor.unite new_unit
    end