mql5/Indicators/MyIndicators/MFI_Pro.md

Money Flow Index (MFI) Professional

1. Summary (Introduction)

The Money Flow Index (MFI) is a momentum oscillator that measures the strength of money flowing into and out of a security. Developed as a "volume-weighted RSI," it combines both price and volume data to identify overbought or oversold conditions.

Our MFI_Pro implementation is a unified, professional version that includes an optional signal line and allows the calculation to be based on either standard or Heikin Ashi price data.

2. Mathematical Foundations and Calculation Logic

The MFI calculation is similar to the RSI, but it uses "Money Flow," which is derived from the Typical Price and Volume.

Required Components

• Period (N): The lookback period for the calculation.
• Price and Volume Data: The High, Low, Close, and Volume of each bar.

Calculation Steps (Algorithm)

1. Calculate the Typical Price (TP): \text{TP}_i = \frac{\text{High}_i + \text{Low}_i + \text{Close}_i}{3}
2. Calculate the Raw Money Flow (RMF): \text{Raw Money Flow}_i = \text{TP}_i \times \text{Volume}_i
3. Determine Positive and Negative Money Flow by comparing the current TP to the previous TP.
4. Calculate the Money Flow Ratio by summing the Positive and Negative Money Flows over the period N.
5. Calculate the Money Flow Index (MFI): \text{MFI}_i = 100 - \frac{100}{1 + \text{Money Flow Ratio}}

3. MQL5 Implementation Details

Our MQL5 implementation follows a modern, object-oriented design to ensure stability, reusability, and maintainability.

• Modular Calculation Engine (MFI_Calculator.mqh): The entire calculation logic is encapsulated within a reusable include file.

  • Composition: The calculator internally uses our universal MovingAverage_Engine.mqh to handle the smoothing of the Signal Line. This allows for advanced smoothing types (like DEMA or TEMA) beyond the standard SMA.

• Optimized Incremental Calculation (O(1)): Unlike basic implementations that recalculate the entire history on every tick, this indicator employs an intelligent incremental algorithm.

  • State Tracking: It utilizes prev_calculated to process only new bars.
  • Persistent Buffers: Internal buffers (Typical Price, Money Flow) persist their state between ticks.
  • Sliding Window: The summation of Money Flow is handled by an efficient sliding window logic that updates incrementally.

• Object-Oriented Design:

  • A base class, CMFICalculator, handles the core MFI algorithm.
  • A derived class, CMFICalculator_HA, inherits from the base class and overrides the data preparation step to use the Typical Price derived from smoothed Heikin Ashi candles.

4. Parameters

• MFI Period (InpMFIPeriod): The lookback period for summing the money flows. (Default: 14).
• Candle Source (InpCandleSource): Allows the user to select the candle type for the Typical Price calculation (Standard or Heikin Ashi).
• Volume Type (InpVolumeType): Allows the user to select between Tick Volume and Real Volume.
• Signal Line Settings:
  • InpDisplayMode: Toggles the visibility of the signal line.
  • InpMAPeriod: The lookback period for the signal line.
  • InpMAMethod: The type of moving average for the signal line. Supports: SMA, EMA, SMMA, LWMA, TMA, DEMA, TEMA.

5. Usage and Interpretation

• Overbought/Oversold Levels: The primary use of the MFI is to identify extreme conditions (typically above 80 and below 20).
• Divergence: This is the MFI's most powerful signal. A bullish divergence occurs when price makes a lower low, but the MFI makes a higher low. A bearish divergence is the opposite.
• Signal Line Crossovers: If the signal line is enabled, crossovers can provide entry and exit signals, similar to other oscillators.
• Caution: In a very strong trend, the MFI can remain in overbought or oversold territory for extended periods.