// Downloaded From https://www.WiseStockTrader.com
// Provided by Cesar Alvarez www.AlvarezQuantTrading.com
// Historical Volatility 
lenPeriod = Param("Periods",100,10,1000,1);

HV = 100 * StDev(log(C/Ref(C,-1)),lenPeriod) * sqrt(252);
Plot(HV, "HV("+lenPeriod+")", ParamColor( "Color", colorRed ), ParamStyle("Style")  );