SignalToNoise indicator

using System;
using cAlgo.API;
using cAlgo.API.Indicators;
using cAlgo.API.Internals;

namespace cAlgo
{
    [Levels(0)]
    [Indicator(IsOverlay = false, AccessRights = AccessRights.None)]
    public class mSignalToNoise : Indicator
    {
        [Parameter("Main Period (21)", DefaultValue = 21)]
        public int inpMainPeriod{ get; set; }
        [Parameter("Smooth Period (7)", DefaultValue = 7)]
        public int inpSmoothPeriod{ get; set; }
        [Parameter("Show Difference as Oscillator", DefaultValue = false)]
        public bool inpShowDifferenceOscillator { get; set; }
        [Parameter("Show Arrows ", DefaultValue = true)]
        public bool inpShowArrows { get; set; }

        [Output("SignalToNoise", LineColor = "Black", PlotType = PlotType.DiscontinuousLine, Thickness = 1)]
        public IndicatorDataSeries outSignalToNoise { get; set; }
        [Output("Signal", LineColor = "Red", PlotType = PlotType.DiscontinuousLine, Thickness = 1)]
        public IndicatorDataSeries outSignal { get; set; }
        
        private IndicatorDataSeries _stn;
        private MovingAverage _smooth;
        private double raw;
        private AverageTrueRange _atr;

        protected override void Initialize()
        {
            _stn = CreateDataSeries();
            _smooth = Indicators.MovingAverage(_stn, inpSmoothPeriod, MovingAverageType.Simple);
            _atr = Indicators.AverageTrueRange(27, MovingAverageType.Simple);
        }

        public override void Calculate(int i)
        {
            raw =0;
            for (int j=1; j<inpMainPeriod-1; j++)
                raw += (1 / Bars.ClosePrices[i-j]) / inpMainPeriod;
            _stn[i] = -10 * Math.Log(raw);

            outSignalToNoise[i] = !inpShowDifferenceOscillator ? _stn[i] : _stn[i] -_smooth.Result[i];
            outSignal[i] = !inpShowDifferenceOscillator ? _smooth.Result[i] : double.NaN;
                        
            if(inpShowArrows)
            {
                if(_stn[i-1] < _smooth.Result[i-1] && _stn[i] > _smooth.Result[i])
                    Chart.DrawIcon("SignalToNoiseUp" + Bars.OpenTimes.Last(0).ToString(), ChartIconType.Star, Bars.OpenTimes.Last(0), Bars.LowPrices.Last(0) - _atr.Result.Last(1), "Teal");
                else
                    Chart.RemoveObject("SignalToNoiseUp" + Bars.OpenTimes.Last(0).ToString());
                
                if(_stn[i-1] > _smooth.Result[i-1] && _stn[i] < _smooth.Result[i])
                    Chart.DrawIcon("SignalToNoiseDown" + Bars.OpenTimes.Last(0).ToString(), ChartIconType.Star, Bars.OpenTimes.Last(0), Bars.HighPrices.Last(0) + _atr.Result.Last(1), "Brown");
                else
                    Chart.RemoveObject("SignalToNoiseDown" + Bars.OpenTimes.Last(0).ToString());
            }
        }
    }
}