diff -up OpenCV-2.2.0/modules/ml/src/gbt.cpp.gcc46 OpenCV-2.2.0/modules/ml/src/gbt.cpp
--- OpenCV-2.2.0/modules/ml/src/gbt.cpp.gcc46	2010-12-05 04:35:25.000000000 +0100
+++ OpenCV-2.2.0/modules/ml/src/gbt.cpp	2012-01-13 10:35:49.724487556 +0100
@@ -1,6 +1,7 @@
 
 #include "precomp.hpp"
 #include <string>
+#include <math.h>
 #include <time.h>
 
 using namespace std;