--- loncom/xml/lonplot.pm	2004/05/26 19:44:20	1.96
+++ loncom/xml/lonplot.pm	2004/06/21 20:04:29	1.97
@@ -1,7 +1,7 @@
 # The LearningOnline Network with CAPA
 # Dynamic plot
 #
-# $Id: lonplot.pm,v 1.96 2004/05/26 19:44:20 matthew Exp $
+# $Id: lonplot.pm,v 1.97 2004/06/21 20:04:29 matthew Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -36,8 +36,17 @@ use Apache::response;
 use Apache::lonxml;
 use Apache::edit;
 
+use vars qw/$weboutputformat $versionstring/;
+
 BEGIN {
-  &Apache::lonxml::register('Apache::lonplot',('gnuplot'));
+    &Apache::lonxml::register('Apache::lonplot',('gnuplot'));
+    #
+    # Determine the version of GNUPLOT
+    $weboutputformat = 'gif';
+    $versionstring = `gnuplot --version`;
+    if ($versionstring =~ /^gnuplot 4/) {
+        $weboutputformat = 'png';
+    }
 }
 
 ## 
@@ -460,7 +469,7 @@ sub end_gnuplot {
 	## return image tag for the plot
 	if ($target eq 'web') {
 	    $result .= <<"ENDIMAGE";
-<img src    = "/cgi-bin/plot.gif?file=$filename.data&output=gif" 
+<img src    = "/cgi-bin/plot.gif?file=$filename.data&output=$weboutputformat" 
      width  = "$plot{'width'}"
      height = "$plot{'height'}"
      align  = "$plot{'align'}"