The trading system based on the JFatlCandle indicator signals with an ability to change the volume of a forthcoming trade depending on the results of the previous trades for this trading system. Trading signals are formed when a bar closes if a trend has changed (which is displayed by candles changing their color).

The block of input EA variables is added for managing volumes of opened positions:

input uint    BuyTotalMMTriger=3; // The number of the last Buy deals to calculate stop loss input uint    BuyLossMMTriger=2;  // The number of losing Buy deals to reduce MM input uint    SellTotalMMTriger=3;// The number of the last Sell deals to calculate stop loss input uint    SellLossMMTriger=2; // The number of losing Sell deals to reduce MM input double  SmallMM_=0.01;      // Share of a deposit in a deal in case of loss input double  MM=0.1;             // Share of a deposit in a deal during normal trading input MarginMode MMMode=LOT;      // Lot value determining method 

In case of such inputs and when selecting from the last five trades, three of which are loss-making in a single direction, the EA opens the next trade in the same direction having the volume of 0.01 lot. If there are less than three loss-making trades out of the last five ones, the position volume is 0.1.

For the generated EA to operate correctly, the compiled files of indicators JFatl.ex5  and JFatlCandle.ex5 should be present in the <terminal_data_directory>\MQL5\Indicators folder.

Default Expert Advisor's input parameters without stops have been used during tests shown below.

Fig. 1. Examples of trades on the chart

Testing results for USDJPY H12 over the year 2017:

Fig. 2. Test results chart