--- loncom/xml/lontexconvert.pm	2008/01/29 11:04:10	1.85
+++ loncom/xml/lontexconvert.pm	2008/07/18 13:09:33	1.88
@@ -1,7 +1,7 @@
 # The LearningOnline Network with CAPA
 # TeX Conversion Module
 #
-# $Id: lontexconvert.pm,v 1.85 2008/01/29 11:04:10 foxr Exp $
+# $Id: lontexconvert.pm,v 1.88 2008/07/18 13:09:33 raeburn Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -85,7 +85,6 @@ $Apache::lontexconvert::messedup=0;
 # into the safe space since opcode checks only occur at compile time
 sub convert_real {
     my ($texstring)=@_;
-    &Apache::lonnet::logthis("convert_real converting '$$texstring");
     my ($xmlstring,$errorstring);
     local $SIG{SEGV}=sub { $Apache::lontexconvert::messedup=1; die; };
     local $SIG{ALRM}=sub { 
@@ -96,14 +95,12 @@ sub convert_real {
     };
     &Apache::lonxml::start_alarm();
     if ($env{'browser.mathml'}) {
-	&Apache::lonnet::logthis("mathml translation");
 	$xmlstring=&tth::ttm($$texstring);
 	$xmlstring=~s/\<math\>/\<math xmlns=\"\&mathns\;\"\>/g;
 	$xmlstring=~s/\<br\>/\<br\/\>/g;
 	$xmlstring=~s/\<p\>/\<p\>\<\/p\>/g;
 	$errorstring.=&tth::ttmerror();
     } else {
-	&Apache::lonnet::logthis("tth translation");
 	$xmlstring=&tth::tth($$texstring);
 	$errorstring.=&tth::ttherror();
 	$xmlstring=~s-</font(\s*)>-</font>-g;
@@ -116,9 +113,9 @@ sub convert_real {
     # reasonably well to &#8660;.  If we get many more of these,
     # we're going to need to have a translation sub.
     #
-    $xmlstring=~s/\\rightleftharpoons/\&\#8660;/g;
+    my $lrharpoon = pack("U", 0x21cc);
+    $xmlstring=~s/\\rightleftharpoons/$lrharpoon/g;
 
-    &Apache::lonnet::logthis("Final result: $xmlstring");
     &Apache::lonxml::end_alarm();
     return ($xmlstring,$errorstring);
 }
@@ -222,7 +219,9 @@ sub jsMath_converted {
 
 sub tex_engine {
     if (exists($env{'form.texengine'})) {
-	return $env{'form.texengine'};
+	if ($env{'form.texengine'} ne '') {
+            return $env{'form.texengine'};
+        }
     }    
     if ($env{'request.course.id'}
 	&& exists($env{'course.'.$env{'request.course.id'}.'.texengine'})) {