--- loncom/homework/default_homework.lcpm	2006/12/15 21:15:42	1.122
+++ loncom/homework/default_homework.lcpm	2008/03/03 19:14:51	1.125
@@ -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 1.122 2006/12/15 21:15:42 www Exp $
+# $Id: default_homework.lcpm,v 1.125 2008/03/03 19:14:51 www Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -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($answer),\$reterror);
     } else {
@@ -256,38 +257,6 @@ sub caparesponse_check {
     return ($result,$reterror)
 }
 
-sub maxima_cas_formula_fix {
-   my ($expression)=@_;
-   return &implicit_multiplication($expression);
-}
-
-sub capa_formula_fix {
-   my ($expression)=@_;
-   return &implicit_multiplication($expression);
-}
-
-sub implicit_multiplication {
-    my ($expression)=@_;
-# Escape scientific notation, so 3e8 does not become 3*e*8
-# 3e8 -> 3&8; 3e-8 -> 3&-8; 3E+8 -> e&+8
-    $expression=~s/(\d+)e([\+\-]*\d+)/$1\&\($2\)/gsi;
-# 3x10^8 -> 3&8; 3*10^-8 -> 3&-8
-    $expression=~s/(\d+)(?:x|\*)10(?:\^|\*\*)([\+\-]*\d+)/$1\&\($2\)/gsi;
-# Fill in multiplication signs
-# a b -> a*b;3 b -> 3*b;3 4 -> 3*4
-    $expression=~s/(\w)\s+(\w)/$1\*$2/gs;
-# )( -> )*(; ) ( -> )*(
-    $expression=~s/\)\s*\(/\)\*\(/gs;
-# 3a -> 3*a; 3( -> 3*(; 3 ( -> 3*(; 3A -> 3*A
-    $expression=~s/(\d)\s*([a-zA-Z\(])/$1\*$2/gs;
-# a ( -> a*(
-    $expression=~s/(\w)\s+\(/$1\*\(/gs;
-# )a -> )*a; )3 -> )*3; ) 3 -> )*3
-    $expression=~s/\)\s*(\w)/\)\*$1/gs;
-# 3&8 -> 3e8; 3&-4 -> 3e-4
-    $expression=~s/(\d+)\&\(([\+\-]*\d+)\)/$1e$2/gs;
-    return $expression;
-}
 
 sub caparesponse_check_list {
     my $responses=$LONCAPA::CAPAresponse_args{'response'};
@@ -449,6 +418,15 @@ 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];