Ruby factorial function

Question

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!

Answer 1

I just wrote my own:

def fact(n)
  if n<= 1
    1
  else
    n * fact( n - 1 )
  end
end

Also, you can define a falling factorial:

def fall_fact(n,k)
  if k <= 0
    1
  else
    n*fall_fact(n - 1, k - 1)
  end
end