--- loncom/xml/lonplot.pm	2004/06/28 15:42:49	1.98
+++ loncom/xml/lonplot.pm	2004/08/17 17:37:56	1.100
@@ -1,7 +1,7 @@
 # The LearningOnline Network with CAPA
 # Dynamic plot
 #
-# $Id: lonplot.pm,v 1.98 2004/06/28 15:42:49 matthew Exp $
+# $Id: lonplot.pm,v 1.100 2004/08/17 17:37:56 matthew Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -43,7 +43,7 @@ BEGIN {
     #
     # Determine the version of GNUPLOT
     $weboutputformat = 'gif';
-    $versionstring = `gnuplot --version`;
+    $versionstring = `gnuplot --version 2>/dev/null`;
     if ($versionstring =~ /^gnuplot 4/) {
         $weboutputformat = 'png';
     }
@@ -954,6 +954,24 @@ sub write_gnuplot_file {
     my $gnuplot_input = '';
     my $curve;
     my $pt = $plot{'texfont'};
+    #
+    # Check to be sure we do not have any empty curves
+    my @curvescopy;
+    foreach my $curve (@curves) {
+        if (exists($curve->{'function'})) {
+            if ($curve->{'function'} !~ /^\s*$/) {
+                push(@curvescopy,$curve);
+            }
+        } elsif (exists($curve->{'data'})) {
+            foreach my $data (@{$curve->{'data'}}) {
+                if (scalar(@$data) > 0) {
+                    push(@curvescopy,$curve);
+                    last;
+                }
+            }
+        }
+    }
+    @curves = @curvescopy;
     # Collect all the colors
     my @Colors;
     push @Colors, $plot{'bgcolor'};