PHPGraphLib科学记数法问题

Question

我正在使用此图表库生成一些基本图表。我遇到的问题是Y轴的值超过一百万的情况，图表以科学记数法表示数字。

我不确定这是PHP问题还是库内的问题。我查看了源代码，但无法解决问题。

这是一个代码示例：

<?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(); 
?> 

以下是此库的来源：
http://www.ebrueggeman.com/phpgraphlib

由于