mql5/Indicators/MyIndicators/Supertrend_Pro.md

Supertrend Professional

1. Summary (Introduction)

The Supertrend indicator, developed by Olivier Seban, is a simple yet effective trend-following indicator. Plotted directly on the price chart, the Supertrend line changes color and position based on the market's trend, acting as a dynamic level of support or resistance.

Our Supertrend_Pro implementation is a unified, professional version that combines three distinct calculation methodologies into a single, flexible indicator:

1. Standard: Classic Supertrend using standard price data for both the trend calculation and the ATR.
2. HA-Hybrid: A smoothed Supertrend based on Heikin Ashi prices, with channel width based on standard, real-market ATR.
3. HA-Pure: A fully smoothed Supertrend where both the trend calculation and the ATR are based on Heikin Ashi data.

2. Mathematical Foundations and Calculation Logic

The Supertrend indicator combines a measure of volatility (Average True Range - ATR) with a central price point to construct upper and lower bands.

Required Components

• ATR (Average True Range): A measure of market volatility.
• Factor (Multiplier): A user-defined multiplier that adjusts the sensitivity.
• Median Price (hl2): The central point for the bands, calculated as (High + Low) / 2.

Calculation Steps (Algorithm)

1. Calculate the Average True Range (ATR).
2. Calculate the Basic Upper and Lower Bands:
   • \text{Upper Basic Band} = \frac{\text{High} + \text{Low}}{2} + (\text{Factor} \times \text{ATR})
   • \text{Lower Basic Band} = \frac{\text{High} + \text{Low}}{2} - (\text{Factor} \times \text{ATR})
3. Calculate the Final Upper and Lower Bands using the "stair-step" logic to ensure bands never move against the trend.
4. Determine the Trend Direction by comparing the closing price to the opposite band.
5. Plot the Supertrend Line:
   • If the trend is up, plot the Final Lower Band.
   • If the trend is down, plot the Final Upper Band.

3. MQL5 Implementation Details

Our MQL5 implementation follows a modern, component-based, object-oriented design.

• Component-Based Design: The Supertrend calculator (Supertrend_Calculator.mqh) reuses our existing, standalone ATR_Calculator.mqh module. This eliminates code duplication and ensures that the ATR component is always our robust, definition-true Wilder's ATR.

• Object-Oriented Logic:

  • The CSupertrendCalculator base class performs the full, state-dependent calculation.
  • The CSupertrendCalculator_HA child class inherits all the complex logic and only overrides the initial data preparation step to use smoothed Heikin Ashi prices.
  • The calculator internally checks the InpAtrSource parameter and instructs its contained ATR_Calculator object to use either standard or Heikin Ashi data, providing all three logical variations within a clean, unified structure.

• Stability via Full Recalculation: We employ a "brute-force" full recalculation within OnCalculate. For a state-dependent indicator like Supertrend, this is the most reliable method.

4. Parameters

• ATR Period (InpAtrPeriod): The lookback period for the ATR calculation. Default is 10.
• Factor (InpFactor): The multiplier applied to the ATR value. Default is 3.0.
• Candle Source (InpCandleSource): Determines the source for the Supertrend's price component ((High+Low)/2 and Close).
• ATR Source (InpAtrSource): Determines the source for the ATR calculation (Standard or Heikin Ashi), allowing you to create "Hybrid" or "Pure" HA versions.

5. Usage and Interpretation

• Trend Identification: A green line below the price indicates an uptrend. A red line above the price indicates a downtrend.
• Trailing Stop-Loss: The indicator is exceptionally well-suited for use as a trailing stop-loss.
• Trade Signals: A change in the indicator's color can be interpreted as a trade signal.
• Caution: Like all trend-following indicators, Supertrend is most effective in trending markets. In sideways or ranging markets, it can produce frequent false signals ("whipsaws").