--- loncom/homework/lonmaxima.pm	2007/05/26 15:51:08	1.14
+++ 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 1.14 2007/05/26 15:51:08 www Exp $
+# $Id: lonmaxima.pm,v 1.16 2007/06/15 21:49:50 albertel Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -60,7 +60,9 @@ sub maximareply {
 
 sub blacklisted {
     my ($cmd)=@_;
-    foreach my $forbidden ('save','load','plot','lisp','includ','compil','file','batch','stringout','translat','stout','stin','block','system') {
+    foreach my $forbidden ('save','load','plot','lisp','includ','compil',
+			   'file','batch','stringout','translat','stout',
+			   'stin','block','system','concat') {
 	if ($cmd=~/$forbidden/s) { return 1; }
     } 
     return 0;
@@ -77,6 +79,7 @@ sub runscript {
     }
     $reply=~s/^\s*//gs;
     $reply=~s/\s*$//gs;
+    &Apache::lonxml::debug("maxima $fullscript \n reply $reply");
     return $reply;
 }
 
@@ -118,7 +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'; }