--- loncom/homework/lonmaxima.pm	2007/05/29 20:56:39	1.15
+++ loncom/homework/lonmaxima.pm	2008/06/10 13:31:38	1.22
@@ -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 1.22 2008/06/10 13:31:38 www Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -62,7 +62,9 @@ sub blacklisted {
     my ($cmd)=@_;
     foreach my $forbidden ('save','load','plot','lisp','includ','compil',
 			   'file','batch','stringout','translat','stout',
-			   'stin','block','system','concat') {
+			   'stin','block','system','concat','read','inchar',
+			   'outchar','ttyoff','with_stdout','writefile',
+			   'reset') {
 	if ($cmd=~/$forbidden/s) { return 1; }
     } 
     return 0;
@@ -121,7 +123,7 @@ 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'; }
@@ -134,7 +136,12 @@ sub maxima_check {
     my $socket=&connect();
     my $reply=&compareterms($socket,$response,$answer);
     &disconnect($socket);
+    # integer to string mappings come from capaParser.h
+    # 1 maps to 'EXACT_ANS'
     if ($reply eq 'true') { return 1; }
+    # 11 maps to 'BAD_FORMULA'
+    if ($reply=~/^Error\:/) { return 11; }
+    # 7 maps to 'INCORRECT'
     return 7;
 }