--- loncom/homework/lonmaxima.pm	2008/08/21 12:08:32	1.25
+++ loncom/homework/lonmaxima.pm	2012/02/17 15:31:04	1.30
@@ -1,7 +1,7 @@
 # The LearningOnline Network with CAPA
 # Interface routines to MAXIMA CAS
 #
-# $Id: lonmaxima.pm,v 1.25 2008/08/21 12:08:32 bisitz Exp $
+# $Id: lonmaxima.pm,v 1.30 2012/02/17 15:31:04 raeburn Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -51,7 +51,7 @@ sub maximareply {
 	print $socket &escape($cmd)."\n";
         my $reply=<$socket>;
         chomp($reply);
-        if ($reply=~/^Incorrect/) { $reply='Error: '.$reply; }
+        if ($reply=~/^Incorrect/i) { $reply='Error: '.$reply; }
         return &unescape($reply);
     } else {
         return 'Error: no connection.';
@@ -61,7 +61,7 @@ sub maximareply {
 sub blacklisted {
     my ($cmd)=@_;
     foreach my $forbidden (
-        '\? ','\?','%i','%o','batch','block'
+        '\? ','\?','%i\d+','%o','batch','block'
        ,'compil','concat','describe','display2d','file','inchar'
        ,'includ','lisp','load','outchar','plot','quit'
        ,'read','reset','save','stin','stout','stringout'
@@ -117,7 +117,9 @@ sub runscript {
 
 sub maxima_cas_formula_fix {
    my ($expression)=@_;
-   return &Apache::response::implicit_multiplication($expression);
+   $expression=&Apache::response::implicit_multiplication($expression);
+   $expression=~s/([^\w\%])pi/$1\%pi/gs;
+   return $expression;
 }
 
 sub maxima_run {