September 2017 Update

Task/Exponentiation-operator/Erlang/exponentiation-operator-1.erl

@@ -1,19 +0,0 @@
-% -spec attribute is for documentation and dialyzer static analysis purposes only.
-% It does not constrain the function like a guard (when ... ).
--spec exp_int(X :: integer(), N :: non_neg_integer()) -> integer().
-
-% X ^ 0
-exp_int(X, 0) when is_integer(X) -> % is_integer guard is required, otherwise X would match anything.
-    1;
-
-% X ^ odd
-exp_int(X, N) when is_integer(X), N >= 1, N rem 2 == 1 ->
-    Part = exp_int(X, (N-1) div 2),
-    X * Part * Part;
-
-% X ^ even
-exp_int(X, N) when is_integer(X), N >= 2, N rem 2 == 0 ->
-    Part = exp_int(X, N div 2),
-    Part * Part.
-
-% X ^ negative is excluded because it would return float.

Task/Exponentiation-operator/Erlang/exponentiation-operator-2.erl

@@ -1,21 +0,0 @@
-% -spec attribute is for documentation and dialyzer static analysis purposes only.
-% It does not constrain the function like a guard (when ... ).
--spec exp_float(X :: float(), N :: integer()) -> float().
-
-% X ^ 0
-exp_float(X, 0) when is_float(X) -> % is_float guard is required, otherwise X would match anything.
-    1.0;
-
-% X ^ negative
-exp_float(X, N) when is_float(X), N < 0 ->
-    1.0 / exp_float(X, -N);
-
-% X ^ even
-exp_float(X, N) when is_float(X), N >= 1, N rem 2 == 1 ->
-    Part = exp_float(X, (N-1) div 2),
-    X * Part * Part;
-
-% X ^ odd
-exp_float(X, N) when is_float(X), N >= 2, N rem 2 == 0 ->
-    Part = exp_float(X, N div 2),
-    Part * Part.

Task/Exponentiation-operator/Forth/exponentiation-operator-3.fth

@@ -1,11 +0,0 @@
-: pow ( n m -- n^m )
-( written in Retro Forth )
-1 2rot
-[
-  dup 1 and 0 <>
-  [ [ tuck * swap ] dip ] ifTrue
-  [ dup * ] dip
-  1 >>
-  dup 0 <>
-] while
-drop drop ;

Task/Exponentiation-operator/Julia/exponentiation-operator.julia

@@ -0,0 +1,7 @@
+function pow(base::Number, exp::Integer)
+  r = one(base)
+  for i = 1:exp
+    r *= base
+  end
+  return r
+end

Task/Exponentiation-operator/Kotlin/exponentiation-operator.kotlin

@@ -0,0 +1,43 @@
+// version 1.0.6
+
+infix fun Int.ipow(exp: Int): Int =
+    when {
+        this ==  1 -> 1
+        this == -1 -> if (exp % 2 == 0) 1 else -1
+        exp <  0   -> throw IllegalArgumentException("invalid exponent")
+        exp == 0   -> 1
+        else       -> {
+            var ans = 1
+            var base = this
+            var e = exp
+            while (e > 0) {
+                if (e and 1 == 1) ans *= base
+                e = e shr 1
+                base *= base
+            }
+            ans
+        }
+    }
+
+infix fun Double.dpow(exp: Int): Double {
+    var ans = 1.0
+    var e   = exp
+    var base = if (e < 0) 1.0 / this else this
+    if (e < 0) e = -e
+    while (e > 0) {
+        if (e and 1 == 1) ans *= base
+        e = e shr 1
+        base *= base
+    }
+    return ans
+}
+
+fun main(args: Array<String>) {
+    println("2  ^ 3   = ${2 ipow 3}")
+    println("1  ^ -10 = ${1 ipow -10}")
+    println("-1 ^ -3  = ${-1 ipow -3}")
+    println()
+    println("2.0 ^ -3 = ${2.0 dpow -3}")
+    println("1.5 ^ 0  = ${1.5 dpow 0}")
+    println("4.5 ^ 2  = ${4.5 dpow 2}")
+}

Task/Exponentiation-operator/Rust/exponentiation-operator.rust

@@ -0,0 +1,24 @@
+extern crate num;
+use num::traits::One;
+use std::ops::Mul;
+
+fn pow<T>(mut base: T, mut exp: usize) -> T
+    where T: Clone + One + Mul<T, Output=T>
+{
+    if exp == 0 { return T::one() }
+    while exp & 1 == 0 {
+        base = base.clone() * base;
+        exp >>= 1;
+    }
+    if exp == 1 { return base }
+    let mut acc = base.clone();
+
+    while exp > 1 {
+        exp >>= 1;
+        base = base.clone() * base;
+        if exp & 1 == 1 {
+            acc = acc * base.clone();
+        }
+    }
+    acc
+}

Task/Exponentiation-operator/Zkl/exponentiation-operator-1.zkl

@@ -0,0 +1,16 @@
+fcn pow(n,exp){
+   reg v;
+   if(n.isType(1)){ // Int
+      if (exp<0) return(if(n*n!=1) 0 else (if(exp.isOdd) n else 1));
+      v=1;
+   }else{
+      if(exp<0){ n=1.0/n; exp=-exp; }
+      v=1.0;
+   }
+   while(exp>0){
+      if(exp.isOdd) v*=n;
+      n*=n;
+      exp/=2;
+   }
+   v
+}

Task/Exponentiation-operator/Zkl/exponentiation-operator-2.zkl

@@ -0,0 +1,4 @@
+println("2^6 = %d".fmt(pow(2,6)));
+println("2^-6 = %d".fmt(pow(2,-6)));
+println("2.71^6 = %f".fmt(pow(2.71,6)));
+println("2.71^-6 = %f".fmt(pow(2.71,-6)));