php - PHPGraphLib scientific notation Issue

I am using this graphing library to generate a few basic graphs. The issue I am having is that is cases where the values for the Y axis are over a million, The graph renders the numbers in scientific notation.

I'm not sure if this is a PHP issue or something within the library. I have looked through the source code but haven't been able to resolve the issue.

Here is a code example:

<?php 
include('phpgraphlib.php'); 
include('phpgraphlib_stacked.php'); 
$graph = new PHPGraphLibStacked(500,300); 
$popularity = array('Windows 7'=>8000000, 'Mac OS 10'=>3500000, 'Fedora'=>900000); 
$cost = array('Windows 7'=>1000000, 'Mac OS 10'=>3000000, 'Fedora'=>9000000); 
$speed = array('Windows 7'=>5000000,'Mac OS 10'=>5000000,'Fedora'=>8000000); 
$graph->addData($popularity, $cost, $speed); 
$graph->setTitle('Operating System Scores'); 
$graph->setTitleLocation('left'); 
$graph->setXValuesHorizontal(TRUE); 
$graph->setTextColor('blue'); 
$graph->setBarColor('#0066CC', '#669999', '#66CCCC'); 
$graph->setLegend(TRUE); 
$graph->setLegendTitle('Popularity', 'Cost', 'Speed'); 
$graph->setDataFormat('comma');
$graph->setupYAxis(20);
$graph->createGraph(); 
?> 
Copy code

Here is the source of this library:
http://www.ebrueggeman.com/phpgraphlib

Thanks