Overriding the array multiplication method to support J-style array multiplication

array_multiplication.rb

class Array

  alias_method :old_times, :*

  def *(multiplier)
    if multiplier.class != Array
      self.old_times multiplier
    else
      if self.size != multiplier.size
        raise "length error"
      else
        self.zip(multiplier).map {|x,y| x * y}
      end
    end
  end

end