grapher(@_, -output=>"g");

    &opt_default(x=>"x", y=>"y", title=>"graph", 
		 filename=>"graph.png", type=>"columns",
 		 style=>"lines", grapher=>"gnuplot", output=>"show");

    my @args = opt_get(@_);
    my $filename = opt_val("filename");
    my $output = opt_val("output");
    my $grapher = opt_val("grapher");

    if ($grapher eq 'gnuplot' && 'MSWin32' ne $^O){
	my $ref_y = shift @args;
	my @command = ({"title" => opt_val("title"),
			    "output file" => "graph/$filename",
			    "x-axis label" => opt_val("x"),
			"y-axis label" => opt_val("y")}, );
	my $i = 1;
	foreach my $ref_x (@args){
	    my $title = opt_val("x$i");
	    $title = "x$i" if ($title eq '');
	    
	    push (@command,
		  [{"title" => $title,
		    "style" => opt_val("style"),
		    "type" => opt_val("type")},
		          $ref_y, $ref_x, ]
		  );
	    $i ++;
	}
    
	gnuplot(@command);
    }else{
	require GD::Graph::lines;
	my $graph = GD::Graph::lines->new(640, 480);
	my $skip = int(scalar(@{$args[0]}) / 10);
	   $graph->set(
		       x_label => opt_val("x"),
		       y_label => opt_val("y"),
		       title => opt_val("title"),
		              x_label_skip => $skip,
		       );
	my $i = 1;
	my @legend;
	while(opt_val("x$i")){
	    push (@legend, opt_val("x$i"));
	    $i ++;
	}
	$graph->set_legend(@legend) if (scalar(@legend));
	my $gd = $graph->plot(\@args);

	open(IMG, '>graph/' . $filename) or die $!;
	binmode IMG;
	print IMG $gd->png;
	close(IMG);
    }

    msg_gimv("graph/$filename") if ($output eq 'show');