CDE

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

@@ -0,0 +1,19 @@
+% -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

@@ -0,0 +1,21 @@
+% -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.