Ruby factorial function

Asked 2010-03-12T17:20:49.090

101

I'm going crazy: Where is the Ruby function for factorial? No, I don't need tutorial implementations, I just want the function from the library. It's not in Math!

I'm starting to doubt, is it a standard library function?

ruby math factorial

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122

Like this is better

(1..n).inject(:*) || 1

answered 2012-09-13T21:57:18.480

class Integer
  def factorial
    return self < 0 ? false : self==0 ? 1 : self.downto(1).inject(:*)
    #Not sure what other libraries say, but my understanding is that factorial of 
    #anything less than 0 does not exist.
  end
end

answered 2013-05-12T23:57:26.900

Ruby factorial function

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