Factorial Recursion

factorial.rb

require 'benchmark'

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

# 0.041621

def tail_factorial(n, acc = 1)
  if n <= 1
    acc
  else
    tail_factorial(n-1, acc * n)
  end
end

Benchmark.bm do |x|
  x.report {factorial(8500)}
  x.report {tail_factorial(8500)}
end 


# Results:

#       user     system      total        real
#    0.050000   0.010000   0.060000 (  0.049929)
#    0.050000   0.010000   0.060000 (  0.071022)