public class New_ATR : IndicatorObject {
      
      [Input]
      public int period { get; set; }
      
      private double trueRange;
      private double averageTrueRange;
      
      private IPlotObject plot1;
      
      public New_ATR(object _ctx):
      base(_ctx){
      
         // default 14 days
         period = 14;         
      }
      
      protected override void Create() {
         // create variable objects, function objects, plot objects etc.
         plot1 = AddPlot(new PlotAttributes("ATR", EPlotShapes.Line, Color.Cyan, Color.Empty, 0, 0, true));
      }
      
      protected override void StartCalc() {
         // assign inputs
      }
      protected override void CalcBar(){
         
         // calculate the value of first bar
         if (Bars.CurrentBar == 0) {            
             trueRange = Bars.High[0] - Bars.Low[0];
            plot1.Set(0, trueRange);
         }
         else {
            // logic from NT7
            //double trueRange = High[0] - Low[0];
            //trueRange = Math.Max(Math.Abs(Low[0] - Close[1]), Math.Max(trueRange, Math.Abs(High[0] - Close[1])));
            //Value.Set(((Math.Min(CurrentBar + 1, Period) - 1 ) * Value[1] + trueRange) / Math.Min(CurrentBar + 1, Period));
            
            trueRange = Bars.High[0] - Bars.Low[0];            
            trueRange = Math.Max(Bars.Low[0] - Bars.Close[1], Math.Max(trueRange, Math.Abs(Bars.High[0] - Bars.Close[1])));
            
            averageTrueRange = ((Math.Min(Bars.CurrentBar + 1, period) - 1 ) * ?????? + trueRange) / Math.Min(Bars.CurrentBar + 1, period);
            
            plot1.Set(0, averageTrueRange);
         }
      }
   }

using System;
 
namespace PowerLanguage.Indicator
{
    public class ITest : IndicatorObject
    {
        private VariableSeries<Double> m_plotVal;
        private IPlotObject Plot1;
 
        public ITest(object ctx) : base(ctx)
        {
            length = 10;
        }
 
        [Input]
        public int length { get; set; }
 
        protected override void Create()
        {
            Plot1 = AddPlot(new PlotAttributes("Test"));
            m_plotVal = new VariableSeries<Double>(this);
        }
 
        protected override void CalcBar() {
            m_plotVal.Value = Bars.Close[length] - Bars.CloseValue;
            Plot1.Set(0, m_plotVal.Value);
        }
    }
}