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Toh4iem9
57 lines
4.5 KiB
Markdown
57 lines
4.5 KiB
Markdown
# Williams' Percent Range (%R)
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## 1. Summary (Introduction)
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Williams' Percent Range, or %R, is a momentum oscillator developed by Larry Williams. It is very similar to the Stochastic Oscillator, but it is plotted on an inverted scale from 0 to -100. Its primary purpose is to identify overbought and oversold conditions in the market.
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The indicator measures the current closing price in relation to the highest high and lowest low over a specified lookback period. It shows where the current price is relative to the recent trading range, helping traders to spot potential exhaustion points in a trend.
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## 2. Mathematical Foundations and Calculation Logic
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The %R formula is straightforward and compares the current close to the recent high-low range.
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### Required Components
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- **Period (N):** The lookback period for the calculation (e.g., 14).
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- **Price Data:** The `High`, `Low`, and `Close` of each bar.
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### Calculation Steps (Algorithm)
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1. **Find the Highest High and Lowest Low:** For each bar, determine the highest high and lowest low over the last `N` periods.
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$\text{Highest High}_N = \text{Max}(\text{High}, N)_i$
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$\text{Lowest Low}_N = \text{Min}(\text{Low}, N)_i$
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2. **Calculate the Williams %R:** Apply the main formula.
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$\text{\%R}_i = -100 \times \frac{\text{Highest High}_N - \text{Close}_i}{\text{Highest High}_N - \text{Lowest Low}_N}$
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The result is a value between 0 and -100. A reading close to 0 means the price is closing near the top of its recent range (overbought), while a reading close to -100 means the price is closing near the bottom of its range (oversold).
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## 3. MQL5 Implementation Details
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Our MQL5 implementation is a self-contained, robust, and clear representation of the Williams %R indicator.
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- **Stability via Full Recalculation:** We employ a "brute-force" full recalculation within the `OnCalculate` function. As a non-recursive indicator, this is a simple and highly stable approach.
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- **Self-Contained Logic:** The indicator is completely self-contained. It does not use any external indicator handles (like `iWPR`). All calculations are performed manually within the `OnCalculate` function using the price data provided.
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- **Reusable Helper Functions:** The calculation of the highest high and lowest low is performed by our standard, reusable `Highest()` and `Lowest()` helper functions, ensuring consistency across our entire indicator toolkit.
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- **Clear, Staged Calculation:** The `OnCalculate` function uses a single, efficient `for` loop to calculate the %R for each bar. The logic is clear and directly follows the mathematical definition of the indicator.
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- **Heikin Ashi Variants:**
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- **`WPR_HeikinAshi.mq5`:** Our toolkit includes a Heikin Ashi version of this indicator. The calculation logic is identical, but it uses the smoothed Heikin Ashi `ha_high`, `ha_low`, and `ha_close` values as its input. This results in a smoother oscillator that reflects the momentum of the underlying Heikin Ashi trend.
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- **`WPRMA_HeikinAshi.mq5`:** We also have a version that adds a moving average signal line to the Heikin Ashi WPR, providing an additional layer of smoothing and potential crossover signals.
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## 4. Parameters
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- **WPR Period (`InpWPRPeriod`):** The lookback period for the indicator. Larry Williams' original recommendation and the most common value is `14`.
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## 5. Usage and Interpretation
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- **Overbought/Oversold Levels:** The primary use of %R is to identify overbought and oversold conditions.
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- **Overbought:** Readings between **0 and -20** are considered overbought. This suggests that the price is near the top of its recent range and may be due for a pullback.
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- **Oversold:** Readings between **-80 and -100** are considered oversold. This suggests that the price is near the bottom of its recent range and may be due for a bounce.
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- **Divergence:** Look for divergences between the %R and the price action. A bearish divergence (higher price highs, lower %R highs) can signal weakening bullish momentum. A bullish divergence (lower price lows, higher %R lows) can signal weakening bearish momentum.
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- **Momentum Failure:** A common signal is when the %R enters the overbought zone, pulls back, and then fails to re-enter the overbought zone on a subsequent price rally. This "momentum failure" can be an early sign of a trend reversal.
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- **Caution:** Like all oscillators, %R can remain in overbought or oversold territory for extended periods during a strong trend. It is not a standalone signal for buying or selling but a tool to gauge momentum within a broader market context.
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