The Recursive Trendline (RTL) indicator shows the trend as a recursive line.

It has two parameters:

• Period - calculation period;
• Applied price - price used for calculations.

RTL[i] = (1 - Alpha)*RTL[i-1] + Alpha*(Price[i] + b0[i] - b0[i-1]),  TOSC[i] = (RTL[i] - EMA(Period, Price))  

Alpha = 2/(Period + 1)  b0[i] = (1 - Alpha)*b0[i-1] + Price[i]  

Possible interpretation: if the line is below the price - Buy, if the line is above the price - Sell.