public Number getClose(int series, int item) {
        DatasetInfo di = getDatasetInfo(series);
        return ((OHLCDataset) di.data).getClose(di.series, item);
    }

    /**
     * Returns the close-value (as a double primitive) for an item within a 
     * series.
     * 
     * @param series  the series (zero-based index).
     * @param item  the item (zero-based index).
     * 
     * @return The close-value.
     */
    public double getCloseValue(int series, int item) {
        double result = Double.NaN;
        Number close = getClose(series, item);
        if (close != null) {
            result = close.doubleValue();   
        }
        return result;