--- loncom/homework/default_homework.lcpm	2008/03/06 14:27:43	1.133
+++ loncom/homework/default_homework.lcpm	2009/12/27 19:40:42	1.146
@@ -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 1.133 2008/03/06 14:27:43 www Exp $
+# $Id: default_homework.lcpm,v 1.146 2009/12/27 19:40:42 www Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -217,7 +217,13 @@ 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 (($type eq '9') || ($type eq '8')) {
+        if ($response=~/\=/) {
+            return ('BAD_FORMULA','Please submit just an expression, not an equation.');
+        } elsif ($response =~ /\,/ and $response !~ /^\s*\{.*\}\s*$/) {
+            return ('BAD_FORMULA');
+        }
+    }
     if ($type eq '9') {
       $result = &maxima_check(&maxima_cas_formula_fix($response),&maxima_cas_formula_fix($answer),\$reterror);
     } else {
@@ -254,7 +260,7 @@ sub caparesponse_check {
 
     &LONCAPA_INTERNAL_DEBUG("RetError $reterror: Answer $answer: Response $response:  type-$type|$tol|$tol_type|$sig:$sig_lbound:$sig_ubound|$unit|");
     &LONCAPA_INTERNAL_DEBUG(" $answer $response $result ");
-    return ($result,$reterror)
+    return ($result,$reterror);
 }
 
 
@@ -303,7 +309,7 @@ sub caparesponse_check_list {
 
     &LONCAPA_INTERNAL_DEBUG("Initial final response :$responses->[0][-1]:");
     my $unit;
-    if ($type eq '' || $type eq 'float') {
+    if ($type eq 'float' || $type eq '') {
 	#for numerical problems split off the unit
 #	if ( $responses->[0][-1]=~ /(.*[^\s])\s+([^\s]+)/ ) {
         if ( $responses->[0][-1]=~ /^([\d\.\,\s\$]*(?:(?:[xX\*]10[\^\*]*|[eE]*)[\+\-]*\d*)*(?:^|\S)\d+)([\$\s\w\^\*\/\(\)\+\-]*[^\d\.\s\,][\$\s\w\^\*\/\(\)\+\-]*)$/ ) {
@@ -316,12 +322,14 @@ sub caparesponse_check_list {
     $unit=~s/\s//;
     foreach my $response (@$responses) {
        foreach my $element (@$response) {	
-          $element =~ s/\s//g;
+          if (($type eq 'float') || (($type eq '') && ($unit ne ''))) {
+              $element =~ s/\s//g;
+          }
           my $appendunit=$unit;
-          if ($unit=~/\%/) {
-             $element=$element/100;
-             $appendunit=~s/\%//;
-          }    
+#          if (($unit=~/\%/) && ($answerunit ne '%'))  {
+#             $element=$element/100;
+#             $appendunit=~s/\%//;
+#          }    
           if (($element==0) && ($unit!~/\w/) && ($answerunit=~/\w/)) {
              $appendunit=$answerunit;
           }
@@ -424,14 +432,49 @@ sub caparesponse_check_list {
 }
 
 sub cas {
-    my ($system,$input)=@_;
+    my ($system,$input,$library)=@_;
     my $output;
+    my $dump;
     if ($system eq 'maxima') {
-       $output=&maxima_eval($input);
+       $output=&maxima_eval($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];
@@ -1024,40 +1067,57 @@ sub sec {
     return $sec;
 }
 
+sub submission {
+   my ($partid,$responseid,$subnumber)=@_;
+   my $sub='';
+   if ($subnumber) { $sub=$subnumber.':'; }
+   return &EXT('user.resource.'.$sub.'resource.'.$partid.'.'.$responseid.'.submission');
+}
+
+sub currentpart {
+   return $external::part;
+}
+
+sub eval_time {
+   my ($timestamp)=@_;
+   unless ($timestamp) { return ''; }
+   return &locallocaltime($timestamp);
+}
+
 sub open_date { 
-    my @dc = split(/\s+/,localtime(&EXT('resource.0.opendate')));
-    return '' if ($dc[0] eq "Wed" and $dc[2] == 31 and $dc[4] == 1969);
-    my @hm = split(/:/,$dc[3]);
-    my $ampm = " am";
-    if ($hm[0] > 12) {
-	$hm[0]-=12;
-	$ampm = " pm";
-    }
-    return $dc[0].', '.$dc[1].' '.$dc[2].', '.$dc[4].' at '.$hm[0].':'.$hm[1].$ampm;
-}
-
-sub due_date { 
-    my @dc = split(/\s+/,localtime(&EXT('resource.0.duedate')));
-    return '' if ($dc[0] eq "Wed" and $dc[2] == 31 and $dc[4] == 1969);
-    my @hm = split(/:/,$dc[3]);
-    my $ampm = " am";
-    if ($hm[0] > 12) {
-	$hm[0]-=12;
-	$ampm = " pm";
-    }
-    return $dc[0].', '.$dc[1].' '.$dc[2].', '.$dc[4].' at '.$hm[0].':'.$hm[1].$ampm;
+    my ($partid)=@_;
+    unless ($partid) { $partid=0; }
+    return &eval_time(&EXT('resource.'.$partid.'.opendate'));
+}
+
+sub due_date {
+    my ($partid)=@_;
+    unless ($partid) { $partid=0; } 
+    return &eval_time(&EXT('resource.'.$partid.'.duedate'));
 }
 
 sub answer_date { 
-    my @dc = split(/\s+/,localtime(&EXT('resource.0.answerdate')));
-    return '' if ($dc[0] eq "Wed" and $dc[2] == 31 and $dc[4] == 1969);
-    my @hm = split(/:/,$dc[3]);
-    my $ampm = " am";
-    if ($hm[0] > 12) {
-	$hm[0]-=12;
-	$ampm = " pm";
-    }
-    return $dc[0].', '.$dc[1].' '.$dc[2].', '.$dc[4].' at '.$hm[0].':'.$hm[1].$ampm;
+    my ($partid)=@_;
+    unless ($partid) { $partid=0; }
+    return &eval_time(&EXT('resource.'.$partid.'.answerdate'));
+}
+
+sub open_date_epoch {
+    my ($partid)=@_;
+    unless ($partid) { $partid=0; }
+    return &EXT('resource.'.$partid.'.opendate');
+}
+
+sub due_date_epoch {
+    my ($partid)=@_;
+    unless ($partid) { $partid=0; }
+    return &EXT('resource.'.$partid.'.duedate');
+}
+
+sub answer_date_epoch {
+    my ($partid)=@_;
+    unless ($partid) { $partid=0; }
+    return &EXT('resource.'.$partid.'.answerdate');
 }
 
 sub array_moments {