added missing header

diff --git a/common/clitkPortability.h b/common/clitkPortability.h
index 63bb6ac66cc311853fe5ebc5bf745cbcb87bc42a..87de4e4a4b3931205a04b821d5a6ffe86815291d 100755 (executable)
--- a/common/clitkPortability.h
+++ b/common/clitkPortability.h
@@ -1,6 +1,8 @@
 #ifndef CLITKPORTABILITY_H
 #define CLITKPORTABILITY_H
 
+#include <cmath>
+
 #if defined(WIN32)
 #  define rint(x)  floor(x+0.5)
 #  define lrint(x) (long)rint(x)