lib/numb/mobius.rb in numb-0.21.0 vs lib/numb/mobius.rb in numb-0.63.0

@@ -1,11 +1,10 @@
 # coding: utf-8
 class Integer
   def mobius
-    case
-      when (self < 1)                 then nil
-      when (square_free? and number_of_distinct_prime_factors.even?) then 1
-      when (square_free? and number_of_distinct_prime_factors.odd?)  then -1
-      when (not square_free?)         then 0
-    end
+   return if self < 1
+   ω < Ω  ? 0 : (-1)**(Ω)
   end
+
+  alias :möbius :mobius
+  alias :μ :mobius
 end