Another update from ingydotnet^djgoku

Task/Exponentiation-operator/00DESCRIPTION

@@ -1,4 +1,4 @@
-Most all programming languages have a built-in implementation of exponentiation.
+Most programming languages have a built-in implementation of exponentiation.
 Re-implement integer exponentiation for both int<sup>int</sup> and float<sup>int</sup> as both a procedure, and an operator (if your language supports operator definition).
 
 If the language supports operator (or procedure) overloading, then an overloaded form should be provided for both int<sup>int</sup> and float<sup>int</sup> variants.

Task/Exponentiation-operator/Elixir/exponentiation-operator.elixir

@@ -0,0 +1,31 @@
+defmodule My do
+  def exp(x,y) when is_integer(x) and is_integer(y) and y>=0 do
+    IO.write("int>   ")         # debug test
+    exp_int(x,y)
+  end
+  def exp(x,y) when is_integer(y) do
+    IO.write("float> ")         # debug test
+    exp_float(x,y)
+  end
+  def exp(x,y), do: (IO.write("       "); :math.pow(x,y))
+
+  defp exp_int(_,0), do: 1
+  defp exp_int(x,y), do: Enum.reduce(1..y, 1, fn _,acc -> x * acc end)
+
+  defp exp_float(_,y) when y==0, do: 1.0
+  defp exp_float(x,y) when y<0, do: 1/exp_float(x,-y)
+  defp exp_float(x,y), do: Enum.reduce(1..y, 1, fn _,acc -> x * acc end)
+end
+
+list = [{2,0}, {2,3}, {2,-2},
+        {2.0,0}, {2.0,3}, {2.0,-2},
+        {0.5,0}, {0.5,3}, {0.5,-2},
+        {-2,2}, {-2,3}, {-2.0,2}, {-2.0,3},
+        ]
+IO.puts "                    ___My.exp___  __:math.pow_"
+Enum.each(list, fn {x,y} ->
+  sxy = "#{x} ** #{y}"
+  sexp = inspect My.exp(x,y)
+  spow = inspect :math.pow(x,y)         # For the comparison
+  :io.fwrite("~10s = ~12s, ~12s~n", [sxy, sexp, spow])
+end)

Task/Exponentiation-operator/Erlang/exponentiation-operator.erl

@@ -0,0 +1,10 @@
+pow(X, Y) when Y < 0 ->
+    1/pow(X, -Y);
+pow(X, Y) when is_integer(Y) ->
+    pow(X, Y, 1).
+
+pow(_, 0, B) ->
+    B;
+pow(X, Y, B) ->
+    B2 = if Y rem 2 =:= 0 -> B; true -> X * B end,
+    pow(X * X, Y div 2, B2).

Task/Exponentiation-operator/Python/exponentiation-operator.py

@@ -1,22 +1,15 @@
->>> import operator
->>> class num(int):
+MULTIPLY = lambda x, y: x*y
+
+class num(float):
+    # the following method has complexity O(b)
+    # rather than O(log b) via the rapid exponentiation
     def __pow__(self, b):
-        print "Empowered"
-        return operator.__pow__(self+0, b)
+        return reduce(MULTIPLY, [self]*b, 1)
 
+# works with ints as function or operator
+print num(2).__pow__(3)
+print num(2) ** 3
 
->>> x = num(3)
->>> x**2
-Empowered
-9
->>> class num(float):
-    def __pow__(self, b):
-        print "Empowered"
-        return operator.__pow__(self+0, b)
-
-
->>> x = num(2.5)
->>> x**2
-Empowered
-6.25
->>>
+# works with floats as function or operator
+print num(2.3).__pow__(8)
+print num(2.3) ** 8

Task/Exponentiation-operator/REXX/exponentiation-operator.rexx

@@ -1,4 +1,4 @@
-/*REXX program to show  various   (integer)  exponentations.            */
+/*REXX program to show  various   (integer)  exponentiations.           */
                                 say center('digits='digits(),79,'─')
 say '17**65   is:'
 say  17**65

Task/Exponentiation-operator/Ruby/exponentiation-operator-1.rb

@@ -2,12 +2,7 @@ class Numeric
   def pow(m)
     raise TypeError, "exponent must be an integer: #{m}" unless m.is_a? Integer
     puts "pow!!"
-
-    # below requires Ruby 1.8.7
     Array.new(m, self).reduce(1, :*)
-
-    # for earlier versions of Ruby
-    #Array.new(m, self).inject(1) { |res, n| res * n }
   end
 end
 

Task/Exponentiation-operator/VBScript/exponentiation-operator.vb

@@ -0,0 +1,23 @@
+Function pow(x,y)
+	pow = 1
+	If y < 0 Then
+		For i = 1 To Abs(y)
+			pow = pow * (1/x)
+		Next
+	Else
+		For i = 1 To y
+			pow = pow * x
+		Next
+	End If
+End Function
+
+WScript.StdOut.Write "2 ^ 0 = " & pow(2,0)
+WScript.StdOut.WriteLine
+WScript.StdOut.Write "7 ^ 6 = " & pow(7,6)
+WScript.StdOut.WriteLine
+WScript.StdOut.Write "3.14159265359 ^ 9 = " & pow(3.14159265359,9)
+WScript.StdOut.WriteLine
+WScript.StdOut.Write "4 ^ -6 = " & pow(4,-6)
+WScript.StdOut.WriteLine
+WScript.StdOut.Write "-3 ^ 5 = " & pow(-3,5)
+WScript.StdOut.WriteLine