Bug 212370 [Regression] Negative value can not be shown both in chart builder and when preview [13]
chart/org.eclipse.birt.chart.engine/src/org/eclipse/birt/chart/computation/withaxes/AxisSubUnit.java
* 
	 * @return
	 */
	public final double getPositiveTotal( )
	{
		if ( bStackTogether )
		{
			return Math.max( dTotal, 0 );
		}
		return dPositiveTotal;
	}
	/**
	 * 
	 * @return
	 */
	public final double getNegativeTotal( )
	{
		if ( bStackTogether )
		{
			return Math.min( dTotal, 0 );
		}
		return dNegativeTotal;
	}
	/**
	 * 
	 * @param dValue
	 * @return
	 */
	public final double valuePercentage( double dValue )
	{