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Contents
# = FILE
#
# interger/factorial.rb
#
# = DESCRIPTION
#
# Factorial extension for Integer class.
#
# = AUTHORS
#
# CREDIT Malte Milatz
#
class Integer
# Calculate the factorial of an integer.
#
# 2.factorial #=> 2
# 3.factorial #=> 6
# 3.factorial #=> 24
#
def factorial
return 1 if zero?
f = 1
2.upto(self) { |n| f *= n }
f
end
#--
# TODO Pick one of these and deprecate the other. But which?
#++
alias_method( :fac, :factorial )
alias_method( :fact, :factorial )
#-- OLD CODE
#def factorial
# return 1 if self == 0
# #self == 0 ? 1 : ( self * (self-1).factorial )
# f = (1..self.abs).inject { |state, item| state * item }
# return self < 0 ? -f : f
#end
#++
end
# _____ _
# |_ _|__ ___| |_
# | |/ _ \/ __| __|
# | | __/\__ \ |_
# |_|\___||___/\__|
#
=begin test
require 'test/unit'
class TCInteger < Test::Unit::TestCase
def test_factorial
assert_equal( 1, 0.factorial )
assert_equal( 1, 1.factorial )
assert_equal( 2, 2.factorial )
assert_equal( 6, 3.factorial )
assert_equal( 24, 4.factorial )
end
end
=end
Version data entries
10 entries across 10 versions & 1 rubygems