RSI Pro Indicator Family (Pro, %B, Oscillator)

1. Summary (Introduction)

This document covers our comprehensive, professionally coded MQL5 implementation of an advanced Relative Strength Index (RSI) indicator family. Moving beyond the classic RSI, this suite transforms the well-known momentum oscillator into a complete, multi-faceted analysis system for measuring the dynamics of momentum itself.

The core of the family is the RSI_Pro indicator, which integrates a fully customizable signal line and optional Bollinger Bands directly onto the RSI values. From this powerful base, we derive two specialized oscillators:

RSI_PercentB: Normalizes the RSI's position relative to its own volatility bands.
RSI_Oscillator: Displays the difference between the RSI and its signal line as a histogram.

All indicators in this family are built on a shared, modular calculation engine and offer a seamless choice between standard price data and smoothed Heikin Ashi data, providing a powerful toolkit for advanced momentum analysis.

2. Mathematical Foundations and Calculation Logic

All indicators in this family are derived from the same core components: the RSI, its moving average, and the standard deviation of the RSI.

Required Components

RSI Period: The lookback period for the base RSI calculation.
Source Price: The price series for the RSI calculation (standard prices or Heikin Ashi Close).
MA Period & Method: The period and type of moving average for the signal line / Bollinger Bands centerline.
Bands Deviation: The standard deviation multiplier for the Bollinger Bands on the RSI.

Calculation Steps (Algorithm)

Prepare Source Price: The engine first prepares the price series. If a standard price is selected, it is used directly. If a Heikin Ashi price is selected, the indicator first calculates the HA values and uses the corresponding HA price series as the source.
Calculate the Base RSI: A standard RSI is calculated on the prepared price series using Wilder's smoothing method.
Calculate the Signal Line / Centerline: The base RSI line is then smoothed using the selected MA Method and MA Period. This creates the signal line for the RSI_Pro and RSI_Oscillator, and the centerline for the Bollinger Bands.
Calculate Bollinger Bands on RSI: Standard Bollinger Bands are calculated based on the RSI values, using the MA line from the previous step as the centerline.
Calculate Derivative Indicators:
- RSI_Oscillator: The difference between the RSI and its signal line. \text{Oscillator}_t = \text{RSI}_t - \text{Signal Line}_t
- RSI_PercentB: Normalizes the RSI's position relative to its bands. \%B_t = \frac{\text{RSI}_t - \text{Lower Band}_t}{\text{Upper Band}_t - \text{Lower Band}_t}

3. MQL5 Implementation Details

Our MQL5 suite is built on a single, shared, modular, and robust calculation engine to ensure consistency and maintainability across the entire indicator family.

Shared Core Engine (RSI_Engine.mqh): The fundamental calculation of Wilder's RSI is outsourced to a shared engine. This ensures that all indicators in the suite (RSI Pro, TDI, StochRSI, etc.) use the exact same, validated mathematical core, eliminating code duplication and potential inconsistencies.
Modular Calculator Engine (RSI_Pro_Calculator.mqh): This calculator orchestrates the RSI_Engine to get the raw RSI data and then adds the advanced layers: the Signal Line (using MovingAverage_Engine) and the Bollinger Bands.
Composition Pattern: The CRSIProCalculator uses Composition to include the CRSIEngine and the CMovingAverageCalculator. This modular approach allows us to easily swap or upgrade components without breaking the entire system.
Drift-Free RSI: We implemented a robust internal buffering system for the Wilder's Smoothing components (Average Gain/Loss) within the RSI_Engine. This prevents the common "RSI Drift" issue seen in many incremental implementations, ensuring that the indicator values remain stable and accurate over time.
Optimized Incremental Calculation (O(1)): All indicators employ an intelligent incremental algorithm.
- State Tracking: It utilizes prev_calculated to process only new bars.
- Persistent Buffers: Internal buffers persist their state between ticks.
- Robust Offset Handling: The engine correctly handles the initialization periods of the chained calculations (RSI -> Signal Line -> Bands).
Object-Oriented Design:
- An elegant inheritance model (CRSIProCalculator and CRSIProCalculator_HA) allows all indicators in the family to dynamically choose the correct calculation engine at runtime based on user input.

4. Parameters

RSI Period (InpPeriodRSI): The lookback period for the base RSI.
Source Price (InpSourcePrice): A comprehensive list of price sources, including all standard prices and a full range of Heikin Ashi prices.
MA Period (InpPeriodMA): The period for the signal line / Bollinger Bands centerline.
MA Method (InpMethodMA): The type of moving average. Supports: SMA, EMA, SMMA, LWMA, TMA, DEMA, TEMA.
Bands Deviation (InpBandsDev): The standard deviation multiplier for the Bollinger Bands on the RSI.
Display Mode: (For RSI_Pro) Controls which components are visible on the chart.

5. Usage and Interpretation

This indicator family allows for a multi-layered analysis of market momentum.

RSI_Pro (The Main Dashboard):
- Use this as the primary tool to get a complete picture. The Bollinger Bands on the RSI define the expected range of momentum. The signal line shows the trend of momentum.
- A crossover of the RSI and its signal line is a basic momentum shift signal.
- The RSI touching its own outer bands signals a statistical extreme in momentum, which is often a more reliable signal than the fixed 70/30 levels.
RSI_Oscillator (The MACD of RSI):
- This provides a clear, histogram-based view of the difference between momentum (RSI) and its trend (Signal Line).
- A zero-line crossover confirms that momentum has crossed its own average, signaling a potential acceleration in price. It is excellent for spotting divergences.
RSI_PercentB (The Normalized View):
- This oscillator normalizes the RSI's position into a 0-1 scale. It provides an objective measure of overbought/oversold conditions based on the momentum's own volatility.
- Values above 1.0 or below 0.0 are clear signals of extreme momentum that may precede a reversal or consolidation.

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