1diff -ur a/include/gestures/include/finger_metrics.h b/include/gestures/include/finger_metrics.h
2--- a/include/gestures/include/finger_metrics.h 1970-01-01 09:00:01.000000000 +0900
3+++ b/include/gestures/include/finger_metrics.h 2018-12-01 16:58:51.590718511 +0900
4@@ -5,6 +5,8 @@
5 #ifndef GESTURES_FINGER_METRICS_H_
6 #define GESTURES_FINGER_METRICS_H_
7
8+#include <math.h>
9+
10 #include "gestures/include/gestures.h"
11 #include "gestures/include/prop_registry.h"
12#include "gestures/include/vector.h"