Add median command (See #14)

rak/algorithm.h

@@ -176,6 +176,26 @@ inline int popcount_wrapper(T t) {
 #endif
 }
 
+// Get the median of an unordered set of numbers of arbitrary
+// type by modifing the underlying dataset
+template <typename T = double, typename _InputIter>
+T median(_InputIter __first, _InputIter __last) {
+  T __med;
+
+  unsigned int __size = __last - __first;
+  unsigned int __middle = __size / 2;
+  _InputIter __target1 = __first + __middle;
+  std::nth_element(__first, __target1, __last);
+  __med = *__target1;
+
+  if (__size % 2 == 0) {
+    _InputIter __target2 = std::max_element(__first, __target1);
+    __med = (__med + *__target2) / 2.0;
+  }
+
+  return __med;
+}
+
 }
 
 #endif