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
if ( dPositiveTotal - dNegativeTotal == 0 )
		{
			return 0;
		}
		
		return ( dValue * 100d ) / ( dPositiveTotal - dNegativeTotal );
	}
	/**
	 * Saves the last position and uses to compute current position by adding
	 * margin
	 * 
	 * @param dValue
	 *            value to check the max or min location
	 * @param dBaseLocation
	 *            base location when last position is null
	 * @param dMargin
	 *            margin location
	 * @see "https://bugs.eclipse.org/bugs/show_bug.cgi?id=182279"
	 */
	public final void setLastPosition( double dValue, double dBaseLocation,
			double dMargin )
	{
		if ( bStackTogether || dValue >= 0 )
		{
			if ( !Double.isNaN( dLastMaxPosition ) )
			{
				dBaseLocation = dLastMaxPosition;
			}
			dBaseLocation += dMargin;
			dLastMaxPosition = dBaseLocation;