function barChart($filename, $ydata, $xdata){

// Create the graph. These two calls are always required
$graph = new Graph(900,500);
$graph->SetScale('textlin');

//(bunch of styling stuff)

// Create the bar plot
$bplot=new BarPlot($ydata);

// Add the plot to the graph
$graph->Add($bplot);

//(more styling stuff)


// Display the graph
$graph->Stroke($filename);

$graph = null;
$bplot = null;

unset($graph);
unset($bplot);

echo "<br><br>".(memory_get_peak_usage(true)/1048576)."<br><br>";
}

// load fonts only once, and define a constant for them
define("GD_FF_FONT0", imageloadfont(dirname(__FILE__) . "/fonts/FF_FONT0.gdf"));
define("GD_FF_FONT1", imageloadfont(dirname(__FILE__) . "/fonts/FF_FONT1.gdf"));
define("GD_FF_FONT2", imageloadfont(dirname(__FILE__) . "/fonts/FF_FONT2.gdf"));
define("GD_FF_FONT1_BOLD", imageloadfont(dirname(__FILE__) . "/fonts/FF_FONT1-Bold.gdf"));
define("GD_FF_FONT2_BOLD", imageloadfont(dirname(__FILE__) . "/fonts/FF_FONT2-Bold.gdf"));

$this->ff_font0 =  imageloadfont(dirname(__FILE__) . "/fonts/FF_FONT0.gdf");
$this->ff_font1 =  imageloadfont(dirname(__FILE__) . "/fonts/FF_FONT1.gdf");
$this->ff_font2 =  imageloadfont(dirname(__FILE__) . "/fonts/FF_FONT2.gdf");
$this->ff_font1_bold =  imageloadfont(dirname(__FILE__) . "/fonts/FF_FONT1-Bold.gdf");
$this->ff_font2_bold =  imageloadfont(dirname(__FILE__) . "/fonts/FF_FONT2-Bold.gdf");

$this->ff_font0 =  GD_FF_FONT0;
$this->ff_font1 =  GD_FF_FONT1;
$this->ff_font2 =  GD_FF_FONT2;
$this->ff_font1_bold =  GD_FF_FONT1_BOLD;
$this->ff_font2_bold =  GD_FF_FONT2_BOLD;