--- loncom/homework/default_homework.lcpm	2008/11/26 18:11:52	1.142
+++ loncom/homework/default_homework.lcpm	2010/01/06 16:59:30	1.147
@@ -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 1.142 2008/11/26 18:11:52 raeburn Exp $
+# $Id: default_homework.lcpm,v 1.147 2010/01/06 16:59:30 www Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -220,7 +220,7 @@ sub caparesponse_check {
     if (($type eq '9') || ($type eq '8')) {
         if ($response=~/\=/) {
             return ('BAD_FORMULA','Please submit just an expression, not an equation.');
-        } elsif ($response =~ /\,/) {
+        } elsif ($response =~ /\,/ and $response !~ /^\s*\{.*\}\s*$/) {
             return ('BAD_FORMULA');
         }
     }
@@ -326,10 +326,20 @@ sub caparesponse_check_list {
               $element =~ s/\s//g;
           }
           my $appendunit=$unit;
-          if (($unit=~/\%/) && ($answerunit ne '%'))  {
-             $element=$element/100;
-             $appendunit=~s/\%//;
-          }    
+# Deal with percentages
+# unit is unit entered by student, answerunit is unit by author
+# Deprecated: divide answer by 100 if student entered percent,
+# but author did not. Too much confusion
+#          if (($unit=~/\%/) && ($answerunit ne '%'))  {
+#             $element=$element/100;
+#             $appendunit=~s/\%//;
+#          }    
+# Author entered percent, student did not
+          if (($unit!~/\%/) && ($answerunit=~/\%/)) {
+             $element=$element*100;
+             $appendunit='%'.$appendunit;
+          }
+# Zero does not need a dimension
           if (($element==0) && ($unit!~/\w/) && ($answerunit=~/\w/)) {
              $appendunit=$answerunit;
           }
@@ -434,14 +444,47 @@ sub caparesponse_check_list {
 sub cas {
     my ($system,$input,$library)=@_;
     my $output;
+    my $dump;
     if ($system eq 'maxima') {
        $output=&maxima_eval($input,$library);
+    } elsif ($system eq 'R') {
+       ($output,$dump)=&r_eval($input,$library,0);
     } else {
        $output='Error: unrecognized CAS';
     }
     return $output;
 }
 
+sub cas_hashref {
+    my ($system,$input,$library)=@_;
+    if ($system eq 'maxima') {
+       return 'Error: unsupported CAS';
+    } elsif ($system eq 'R') {
+       return &r_eval($input,$library,1);
+    } else {
+       return 'Error: unrecognized CAS';
+    }
+}
+
+#
+# cas_hashref_entry takes a list of indices and gets the entry in a hash generated by Rreturn.
+# Call: cas_hashref_entry(Rvalue, index1, index2, ...) where Rvalue is a hash returned by Rreturn.
+# Rentry will return the first scalar value it encounters (ignoring excess indices).
+# If an invalid key is given, it returns undef.
+#
+sub cas_hashref_entry {
+    return &Rentry(@_);
+}
+
+#
+# cas_hashref_array takes a list of indices and gets a column array from a hash generated by Rreturn.
+# Call: cas_hashref_array(Rvalue, index1, index2, ...) where Rvalue is a hash returned by Rreturn.
+# If an invalid key is given, it returns undef.
+#
+sub cas_hashref_array {
+    return &Rarray(@_);
+}
+
 sub tex {
     if ( $external::target eq "tex" ) {
 	return $_[0];