--- loncom/xml/lontexconvert.pm	2006/09/06 19:43:22	1.77
+++ loncom/xml/lontexconvert.pm	2008/02/06 10:16:00	1.87
@@ -1,7 +1,7 @@
 # The LearningOnline Network with CAPA
 # TeX Conversion Module
 #
-# $Id: lontexconvert.pm,v 1.77 2006/09/06 19:43:22 albertel Exp $
+# $Id: lontexconvert.pm,v 1.87 2008/02/06 10:16:00 foxr Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -108,6 +108,14 @@ sub convert_real {
     $xmlstring=~s/^\s*\<br clear\=\"all\"/\<br/s;
     $xmlstring=~s/^\s*//;
     $xmlstring=~s/\s*$//;
+    #
+    # \rightleftharpoons is not converted by tth but maps
+    # reasonably well to &#8660;.  If we get many more of these,
+    # we're going to need to have a translation sub.
+    #
+    my $lrharpoon = pack("U", 0x21cc);
+    $xmlstring=~s/\\rightleftharpoons/$lrharpoon/g;
+
     &Apache::lonxml::end_alarm();
     return ($xmlstring,$errorstring);
 }
@@ -151,7 +159,7 @@ ENDCONV
 
 sub clean_out_math_mode {
     my ($texstring)=@_;
-    $$texstring=~s/(?!\\)\$//g;
+    $$texstring=~s/(?<!\\)\$//g;
     $$texstring=~s/\\[\)\(\]\[]//g;
     $$texstring=~s/\\ensuremath//g;
     return '';
@@ -184,26 +192,51 @@ sub jsMath_converted {
 	push(@jsMath_sent_header,0);
     }
     sub jsMath_header {
+	if (!@jsMath_sent_header) {
+	    &Apache::lonnet::logthis("mismatched calls of jsMath_header and jsMath_process");
+	    return '';
+	}
 	return '' if $jsMath_sent_header[-1];
 	$jsMath_sent_header[-1]=1;
 	return
             '<script type="text/javascript">
                      function NoFontMessage () {}
+                     jsMath = {Parser: {prototype: {environments: {\'eqnarray*\' :[\'Array\',null,null,\'rcl\',[5/18,5/18],3,\'D\']}}}};
                    </script>'."\n".
 	    '<script type="text/javascript" src="/adm/jsMath/jsMath.js"></script>'."\n";
     }
     sub jsMath_process {
 	my $state = pop(@jsMath_sent_header);
 	return '' if !$state;
-	return '<script type="text/javascript">jsMath.Process()</script>';
+	return "\n".
+	    '<script type="text/javascript">jsMath.Process()</script>'."\n";
+    }
+    sub jsMath_state {
+	my ($level) = @_;
+	return $jsMath_sent_header[$level];
+    }
+}
+
+sub tex_engine {
+    if (exists($env{'form.texengine'})) {
+	return $env{'form.texengine'};
+    }    
+    if ($env{'request.course.id'}
+	&& exists($env{'course.'.$env{'request.course.id'}.'.texengine'})) {
+	return $env{'course.'.$env{'request.course.id'}.'.texengine'};
+    }
+    if (exists($env{'environment.texengine'})) {
+	return $env{'environment.texengine'};
     }
+    return 'tth';
 }
 
 sub init_math_support {
+    my ($inherit_jsmath) = @_;
     &init_tth();
     &Apache::lontexconvert::jsMath_push();
-    if ($env{'environment.texengine'} eq 'jsMath' ||
-	$env{'form.texengine'}        eq 'jsMath' ) {
+    if (lc(&tex_engine()) eq 'jsmath' ||
+	($inherit_jsmath && &jsMath_state(-2))) {
 	return &Apache::lontexconvert::jsMath_header();
     }
     return;
@@ -227,7 +260,7 @@ sub mimetex_converted {
 
 sub converted {
     my ($string,$mode)=@_;
-    if ($mode eq '') { $mode=$env{'environment.texengine'}; }
+    if ($mode eq '') { $mode = &tex_engine(); }
     if ($mode =~ /tth/i) {
 	return &tth_converted($string);
     } elsif ($mode =~ /jsmath/i) {
@@ -266,8 +299,8 @@ sub smiley {
 		 '\:\-(X|\#)' => 'lipsrsealed',
 		 '\:\-S' => 'huh');
     my $iconpath=$Apache::lonnet::perlvar{'lonIconsURL'};
-    foreach (keys %smileys) {
-	$expression=~s/$_/\<img src="$iconpath\/$smileys{$_}.gif" \/\>/gs; 
+    foreach my $smiley (keys(%smileys)) {
+	$expression=~s/$smiley/\<img src="$iconpath\/$smileys{$smiley}.gif" \/\>/gs; 
     }
     return $expression;
 }
@@ -278,27 +311,34 @@ sub msgtexconverted {
     &init_tth();
     my $outmessage='';
     my $tex=0;
-    foreach (split(/(?:\&lt\;|\<)\/*m\s*(?:\&gt\;|\>)/i,$message)) {
+    foreach my $fragment (split(/(?:\&lt\;|\<)\/*m\s*(?:\&gt\;|\>)/i,$message)) {
 	if ($tex) {
 	    if ($email) {
-		$outmessage.='</pre><tt>'.&to_convert($_).'</tt><pre>'; $tex=0;
+		$outmessage.='</pre><tt>'.&to_convert($fragment).'</tt><pre>';
+		$tex=0;
 	    } else {
-		$outmessage.=&to_convert($_); $tex=0;
+		$outmessage.=&to_convert($fragment);
+		$tex=0;
 	    }
 	} else {
-            $outmessage.=&smiley($_); $tex=1;
+            $outmessage.=&smiley($fragment);
+	    $tex=1;
 	}
     }
     $message=$outmessage; $outmessage=''; $tex=0;
-    foreach (split(/(?:\&lt\;|\<)\/*algebra\s*(?:\&gt\;|\>)/i,$message)) {
+    foreach my $fragment (split(/(?:\&lt\;|\<)\/*algebra\s*(?:\&gt\;|\>)/i,
+				$message)) {
 	if ($tex) {
 	    if ($email) {
-		$outmessage.='</pre><tt>'.&algebra($_,'web').'</tt><pre>'; $tex=0;
+		$outmessage.='</pre><tt>'.&algebra($fragment,'web').'</tt><pre>';
+		$tex=0;
 	    } else {
-		$outmessage.=&algebra($_,'web'); $tex=0;
+		$outmessage.=&algebra($fragment,'web');
+		$tex=0;
 	    }
 	} else {
-            $outmessage.=$_; $tex=1;
+            $outmessage.=$fragment;
+	    $tex=1;
 	}
     }
     if (wantarray) {
<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">
<html><head>
<title>500 Internal Server Error</title>
</head><body>
<h1>Internal Server Error</h1>
<p>The server encountered an internal error or
misconfiguration and was unable to complete
your request.</p>
<p>Please contact the server administrator at 
 root@localhost to inform them of the time this error occurred,
 and the actions you performed just before this error.</p>
<p>More information about this error may be available
in the server error log.</p>
</body></html>