Add std::ceil_divide

tstl/include/math.hpp

@@ -0,0 +1,20 @@
+//=======================================================================
+// Copyright Baptiste Wicht 2013-2016.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+//  http://www.boost.org/LICENSE_1_0.txt)
+//=======================================================================
+
+#ifndef MATH_HPP
+#define MATH_HPP
+
+namespace std {
+
+template<typename T>
+T ceil_divide(T base, T divisor){
+    return (base + divisor - 1) / divisor;
+}
+
+} //end of namespace std
+
+#endif