private int getDoubleIndex(double num)
    {
        int index = itsDoubleTableTop;
        if (index == 0) {
            itsData.itsDoubleTable = new double[64];
        } else if (itsData.itsDoubleTable.length == index) {
            double[] na = new double[index * 2];
            System.arraycopy(itsData.itsDoubleTable, 0, na, 0, index);
            itsData.itsDoubleTable = na;
        }
        itsData.itsDoubleTable[index] = num;
        itsDoubleTableTop = index + 1;
        return index;
    }