--- include/vamos/geometry/Three_Vector.h.orig	Thu Feb  3 12:17:54 2005
+++ include/vamos/geometry/Three_Vector.h	Sat Feb  5 20:11:47 2005
@@ -19,6 +19,7 @@
 #define _THREE_VECTOR_H_
 
 #include <iostream>
+#include <cmath>
 
 // A three-element vector.  Useful for representing physical quantites
 // like position, veocity or force.