diff --git a/jacobi/serial/not_opt/src/tools.c b/jacobi/serial/not_opt/src/tools.c
index be2761d170c23fde4d5d4aeda54af00e56abf3ce..f96011481343ee575cddcf26dd3b7d0f39c8cb5b 100644
--- a/jacobi/serial/not_opt/src/tools.c
+++ b/jacobi/serial/not_opt/src/tools.c
@@ -52,6 +52,8 @@ void Show_2DdblArray(const MyData **const A,
 double seconds()
 {
   struct timeval tmp;
+
+  /** could be improved ***/
   gettimeofday(&tmp, (struct timezone *)0);
   double sec = tmp.tv_sec + ((double)tmp.tv_usec)/1000000.0;