gistfile1.rb

# ... snip

NArray.class_eval do
  def sign
    a = []
    self.each do |x|
      a << x.sign
    end
    a
  end

  def eql_items? other
    raise(ArgumentError, "Argument is not an Array") unless other.kind_of? NArray
    raise(ArgumentError, "Arrays dont' have the same number of elements") if self.size != other.size
    output = []
    self.each_with_index do |x, i|
      output[i] = x == other[i]
    end
    return output
  end
end

# ... snip