--- loncom/xml/lonxml.pm	2016/02/20 00:12:45	1.555
+++ loncom/xml/lonxml.pm	2017/09/24 01:52:53	1.558
@@ -1,7 +1,7 @@
 # The LearningOnline Network with CAPA
 # XML Parser Module 
 #
-# $Id: lonxml.pm,v 1.555 2016/02/20 00:12:45 raeburn Exp $
+# $Id: lonxml.pm,v 1.558 2017/09/24 01:52:53 raeburn Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -69,6 +69,7 @@ use Safe();
 use Safe::Hole();
 use Math::Cephes();
 use Math::Random();
+use Math::Calculus::Expression();
 use Opcode();
 use POSIX qw(strftime);
 use Time::HiRes qw( gettimeofday tv_interval );
@@ -345,9 +346,9 @@ sub latex_special_symbols {
     } else {
 	$string=~s/\\/\\ensuremath{\\backslash}/g;
 	$string=~s/\\\%|\%/\\\%/g;
-	$string=~s/\\{|{/\\{/g;
+	$string=~s/\\\{|\{/\\{/g;
 	$string=~s/\\}|}/\\}/g;
-	$string=~s/\\ensuremath\\{\\backslash\\}/\\ensuremath{\\backslash}/g;
+	$string=~s/\\ensuremath\\\{\\backslash\\}/\\ensuremath{\\backslash}/g;
 	$string=~s/\\\$|\$/\\\$/g;
 	$string=~s/\\\_|\_/\\\_/g;
         $string=~s/([^\\]|^)(\~|\^)/$1\\$2\\strut /g;
@@ -819,6 +820,7 @@ sub init_safespace {
   $safehole->wrap(\&Apache::functionplotresponse::fpr_objectcoords,$safeeval,'&fpr_objectcoords');
   $safehole->wrap(\&Apache::functionplotresponse::fpr_vectorlength,$safeeval,'&fpr_vectorlength');
   $safehole->wrap(\&Apache::functionplotresponse::fpr_vectorangle,$safeeval,'&fpr_vectorangle');
+  $safehole->wrap(\&Math::Calculus::Expression::math_calculus_expression,$safeeval,'&math_calculus_expression');
 
 #  use Data::Dumper;
 #  $safehole->wrap(\&Data::Dumper::Dumper,$safeeval,'&LONCAPA_INTERNAL_Dumper');
@@ -991,7 +993,7 @@ sub decreasedepth {
 sub get_id {
     my ($parstack,$safeeval)=@_;
     my $id= &Apache::lonxml::get_param('id',$parstack,$safeeval);
-    if ($env{'request.state'} eq 'construct' && $id =~ /([._]|[^\w\d\s[:punct:]])/) {
+    if ($env{'request.state'} eq 'construct' && $id =~ /([._]|[^\w\s\-])/) {
 	&error(&mt('ID [_1] contains invalid characters. IDs are only allowed to contain letters, numbers, spaces and -','"<tt>'.$id.'</tt>"'));
     }
     if ($id =~ /^\s*$/) { $id = $Apache::lonxml::curdepth; }