--- loncom/homework/default_homework.lcpm	2006/12/15 22:11:43	1.123
+++ loncom/homework/default_homework.lcpm	2008/03/05 16:06:39	1.127
@@ -1,7 +1,7 @@
 # The LearningOnline Network with CAPA 
 # used by lonxml::xmlparse() as input variable $safeinit to Apache::run::run()
 #
-# $Id: default_homework.lcpm,v 1.123 2006/12/15 22:11:43 www Exp $
+# $Id: default_homework.lcpm,v 1.127 2008/03/05 16:06:39 www Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -166,7 +166,7 @@ sub caparesponse_check {
 	$response=~s/[\s,]//g;
     }
     if ($type eq 'float' && $unit=~/\$/) {
-	if ($response!~/^\$/)  { return ('NO_UNIT', undef); }
+	if ($response!~/^\$|\$$/)  { return ('NO_UNIT', undef); }
 	$response=~s/\$//g;
     }
     if ($type eq 'float' && $unit=~/\,/ && (&check_commas($response)<0)) {
@@ -217,6 +217,7 @@ sub caparesponse_check {
 
     my $reterror="";
     my $result;
+    if ((($type eq '9') || ($type eq '8')) && ($response=~/\=/)) { return ('BAD_FORMULA','Please submit just an expression, not an equation.'); }
     if ($type eq '9') {
       $result = &maxima_check(&maxima_cas_formula_fix($response),&maxima_cas_formula_fix($answer),\$reterror);
     } else {
@@ -318,7 +319,8 @@ sub caparesponse_check_list {
     $unit=~s/\s//;
     if ($unit ne '') {
 	foreach my $response (@$responses) {
-	    foreach my $element (@$response) {	    
+	    foreach my $element (@$response) {	
+                $element =~ s/\s//g;    
 		$element .= " $unit";
 	    }
 	}
@@ -417,6 +419,15 @@ sub caparesponse_check_list {
     return ($final_award,$final_msg);
 }
 
+sub cas {
+    my ($system,$input)=@_;
+    my $output;
+    if ($system eq 'maxima') {
+       $output=&maxima_eval($input);
+    }
+    return $output;
+}
+
 sub tex {
     if ( $external::target eq "tex" ) {
 	return $_[0];