--- loncom/xml/lontexconvert.pm	2005/02/11 16:46:38	1.43
+++ loncom/xml/lontexconvert.pm	2005/02/24 08:32:11	1.49
@@ -1,7 +1,7 @@
 # The LearningOnline Network with CAPA
 # TeX Conversion Module
 #
-# $Id: lontexconvert.pm,v 1.43 2005/02/11 16:46:38 www Exp $
+# $Id: lontexconvert.pm,v 1.49 2005/02/24 08:32:11 albertel Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -212,6 +212,54 @@ sub msgtexconverted {
     }
 }
 
+sub algebra {
+    use AlgParser;
+
+    my ($string,$target)=@_;
+    my $parser = new AlgParserWithImplicitExpand;
+    $string=&prepare_algebra($string);
+    my $ret = $parser->parse($string);
+    my $result='['.&mt('Algebra unconverted due to previous errors').']';
+    if ( ref($ret) ) {
+	$parser->tostring();
+	$parser->normalize();
+	my $latex=$parser->tolatex();
+	$latex=&postprocess_algebra($latex);
+	$latex='$'.$latex.'$';
+	if ($target eq 'web' || $target eq 'analyze') {
+	    $result = &converted(\$latex);
+	} else {
+	    $result = $latex;
+	}
+    } else {
+	&Apache::lonxml::error($parser->{'htmlerror'});
+    }
+}
+
+sub prepare_algebra {
+    my ($string)=@_;
+
+    # change some multi character operators into single character operators
+    $string =~ s/<>/\#/g;
+    $string =~ s/<\=/\%/g;
+    $string =~ s/>\=/\!/g;
+    
+    # makes the decision about what is a minus sign easier
+    $string =~ s/([\=\>\<\%\!\#] *)-/$1 zeroplace -/g;
+
+    return $string;
+}
+
+sub postprocess_algebra {
+    my ($string)=@_;
+    
+    # exapnd out some operators
+    $string =~ s/\#/\\not= /g;
+    $string =~ s/\%/\\leq /g;
+    $string =~ s/\!/\\geq /g;
+
+    return $string;
+}
 1;
 __END__