RVOL Pro (Relative Volume)

1. Summary (Introduction)

Relative Volume (RVOL) is a crucial tool for professional traders to validate price action and gauge institutional interest. Instead of displaying absolute volume, which can be misleading, RVOL measures the current bar's volume as a multiple of its recent average. This instantly highlights periods of unusually high or low activity.

The RVOL_Pro indicator provides a clean, multi-color histogram for immediate visual feedback, allowing traders to confirm breakouts, spot potential reversals (climactic volume), and identify low-participation moves that might be traps.

2. Mathematical Foundations and Calculation Logic

The core of the RVOL indicator is a simple yet powerful ratio that contextualizes volume.

Required Components

Current Volume: The volume of the current bar (Volume_i).
Average Volume: A simple moving average (SMA) of the volume over the N preceding bars.

Calculation Steps (Algorithm)

Calculate the Average Volume: Compute the SMA of the volume for the N bars prior to the current bar. \text{Average Volume}_{i} = \frac{1}{N} \sum_{k=1}^{N} \text{Volume}_{i-k}
Calculate the RVOL Ratio: Divide the current bar's volume by the calculated average. \text{RVOL}_i = \frac{\text{Volume}_i}{\text{Average Volume}_i}

An RVOL value of 2.5 means the current bar's volume is 2.5 times higher than the recent average, indicating significant market activity.

3. MQL5 Implementation Details

Modular Calculation Engine (RVOL_Calculator.mqh): The entire calculation logic is encapsulated within the CRVOLCalculator class. This engine is lightweight, stateless within itself (relying on passed data), and can be reused in scripts or Expert Advisors.
Optimized Incremental Calculation (O(1) per Bar): The indicator utilizes prev_calculated to ensure that calculations are only performed on new or changed bars. The core logic involves a loop over the last N bars to compute the average, which is a constant-time operation for each new bar, guaranteeing high performance and zero lag.
Visual Signaling (DRAW_COLOR_HISTOGRAM): The wrapper RVOL_Pro.mq5 uses a multi-color histogram for intuitive signaling. It employs two buffers: one for the RVOL value (INDICATOR_DATA) and one for the color index (INDICATOR_COLOR_INDEX). This allows the color of each bar in the histogram to change dynamically based on user-defined thresholds.

4. Parameters

Calculation Settings:
- InpPeriod: The lookback period for calculating the average volume. (Default: 20).
- InpVolumeType: The type of volume to use (VOLUME_TICK or VOLUME_REAL). VOLUME_REAL is recommended for exchange-traded instruments where available.
Visual Settings:
- InpLevelHigh: The threshold above which volume is considered "High". (Default: 1.5).
- InpLevelExtreme: The threshold above which volume is considered "Extreme". (Default: 2.5).
- InpColorNormal, InpColorHigh, InpColorExtreme: Customizable colors for the three volume states, allowing for easy visual identification of market activity.

5. Usage and Interpretation

Breakout Confirmation: A price breakout from a range or pattern accompanied by RVOL > 1.5 has a higher probability of being valid and indicates strong participation in the move.
Exhaustion / Climactic Volume: An extreme RVOL spike (> 2.5 or 3.0) at the end of a prolonged trend can signal a reversal.
- Blow-off Top: Extreme RVOL on a large bullish candle after a long uptrend.
- Capitulation Bottom: Extreme RVOL on a large bearish candle after a long downtrend.
Lack of Interest: A price move (especially a breakout attempt) on low RVOL (< 0.8) suggests a lack of institutional conviction and increases the likelihood of a "fakeout" or trap.
Absorption (Advanced): High RVOL on a small-bodied candle (Doji/spinning top) near a key support/resistance level can signal that large passive orders are "absorbing" the aggressive market orders, often preceding a reversal.

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