class Integer
Public Instance Methods
!()
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# File lib/probaberry/counting.rb, line 2 def ! if self > 0 (1..self).reduce :* elsif self.zero? 1 else raise ArgumentError, "No factorial for #{self}" end end
choose(r)
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# File lib/probaberry/counting.rb, line 15 def choose r raise ArgumentError, "r = #{r} is outside 0..#{self}" if r < 0 or r > self (self.!).fdiv((self - r).!).fdiv(r.!).to_i end