int itemCount = dataset.getItemCount(series);
                for (int item = 0; item < itemCount; item++) {
                    double delta = vdataset.getVectorYValue(series, item);
                    if (delta < 0.0) {
                        uvalue = vdataset.getYValue(series, item);
                        lvalue = uvalue + delta;
                    }
                    else {
                        lvalue = vdataset.getYValue(series, item);
                        uvalue = lvalue + delta;
                    }
                    minimum = Math.min(minimum, lvalue);
                    maximum = Math.max(maximum, uvalue);