diff -Nur mpb-1.4.2.orig/mpb-ctl/matrix-smob.c mpb-1.4.2/mpb-ctl/matrix-smob.c
--- mpb-1.4.2.orig/mpb-ctl/matrix-smob.c	2002-09-13 19:27:35.000000000 +0100
+++ mpb-1.4.2/mpb-ctl/matrix-smob.c	2008-11-25 18:20:11.000000000 +0000
@@ -17,6 +17,7 @@
 
 #include <stdio.h>
 #include <stdlib.h>
+#include <math.h>
 
 #include "../src/config.h"