private void checkPointsToValue(RectangleEdge edge, Rectangle2D plotArea) {
         assertEquals("Right most point on the axis should be end of range.",
                 this.axis.getUpperBound(), this.axis.java2DToValue(
                 plotArea.getX() + plotArea.getWidth(), plotArea, edge), 
                 EPSILON);

         assertEquals("Left most point on the axis should be beginning of "
                 + "range.", this.axis.getLowerBound(), 
                 this.axis.java2DToValue(plotArea.getX(), plotArea, edge), 
                 EPSILON);

         assertEquals("Center point on the axis should geometric mean of the "
                 + "bounds.", Math.sqrt(this.axis.getUpperBound() 
                 * this.axis.getLowerBound()), this.axis.java2DToValue(
                 plotArea.getX() + (plotArea.getWidth() / 2), plotArea, edge), 
                 EPSILON);