public static double StDev(IList<double> candles, IList<double> SMAs, int curbar, int period)
        {
            int start = curbar - period + 1;
            if (start < 0)
            {
                start = 0;
            }
            period = curbar - start + 1;
            double sum = 0;
            while (start <= curbar && start < candles.Count)
            {
                var s = candles[start] - SMAs[curbar];
                sum += s*s;
                start++;
            }
            var n = Math.Min(period, curbar + 1);
            return Math.Sqrt(sum/n);
        }