Index: mttroot/mtt/cc/include/useful-functions.hh
==================================================================
--- mttroot/mtt/cc/include/useful-functions.hh
+++ mttroot/mtt/cc/include/useful-functions.hh
@@ -17,10 +17,11 @@
 typedef unsigned int bool;
 const bool true = 1;
 const bool false = 0;
 */
 #else
+#include <cmath>
 #define cast_to_double	static_cast<double>
 using std::pow;
 #endif /* ! __cplusplus */