grader-tf.c:108: warning: implicit declaration of function 'log'

--- src/grader-tf.c.orig	Fri Nov 21 00:30:10 2008
+++ src/grader-tf.c	Fri Nov 21 00:30:25 2008
@@ -21,6 +21,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <math.h>
 #include "libots.h"
 
 /*Grader - using the Term frequency algorithm. Will give each line a score*/