diff -up freefem++-3.8/configure.ac.ld freefem++-3.8/configure.ac
--- freefem++-3.8/configure.ac.ld	2010-02-25 22:41:45.000000000 +0100
+++ freefem++-3.8/configure.ac	2010-02-25 22:53:52.000000000 +0100
@@ -229,6 +229,8 @@ AC_LANG(C++)
 # Some useful libraries
 
 AC_CHECK_LIB(pthread,pthread_create,ff_pthread="-lpthread",ff_pthread="")
+AC_CHECK_LIB(m,sqrt,ff_math="-lm",ff_math="")
+AC_SUBST(LIBSMATH,$ff_math)
 
 # Necessary absolute pathname for local directory when some libraries
 # are used from several different locations (for instance locally in
diff -up freefem++-3.8/src/medit/Makefile.am.ld freefem++-3.8/src/medit/Makefile.am
--- freefem++-3.8/src/medit/Makefile.am.ld	2008-12-02 11:19:25.000000000 +0100
+++ freefem++-3.8/src/medit/Makefile.am	2010-02-25 22:54:06.000000000 +0100
@@ -17,7 +17,7 @@ chrono.h	extern.h	image.h		mesh.h \
 eigenv.h	grafic.h	medit.h		sproto.h 
 
 
-LDADD= ../libMesh/libMesh.a $(LIBSGLUT)
+LDADD= ../libMesh/libMesh.a $(LIBSGLUT) $(LIBSMATH)
 INCLUDES=-I../libMesh
 BUILT_SOURCES=compil.date
 compil.date: $(ffmedit_SOURCES)