--- loncom/homework/lonmaxima.pm	2007/05/29 20:56:39	1.15
+++ loncom/homework/lonmaxima.pm	2007/06/15 21:49:50	1.16
@@ -1,7 +1,7 @@
 # The LearningOnline Network with CAPA
 # Interface routines to MAXIMA CAS
 #
-# $Id: lonmaxima.pm,v 1.15 2007/05/29 20:56:39 albertel Exp $
+# $Id: lonmaxima.pm,v 1.16 2007/06/15 21:49:50 albertel Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -121,7 +121,7 @@ sub maxima_eval {
 
 sub compareterms {
     my ($socket,$terma,$termb)=@_;
-    my $difference=$terma.'-'.$termb;
+    my $difference=$terma.'-('.$termb.')';
     if (&blacklisted($difference)) { return 'Error: blacklisted'; }
     my $reply=&maximareply($socket,'trigsimp(trigreduce('.$difference.'));');
     if ($reply=~/^\s*0\s*$/) { return 'true'; }