RSX - Jurik Relative Strength X

RSX is a noise-free version of the Relative Strength Index (RSI) developed by Mark Jurik. It eliminates the lag and choppiness associated with standard RSI and its smoothed variants. RSX preserves the 0-100 bounded range and turning points of RSI but provides a much smoother signal, making it easier to identify trends and reversals without false signals from whipsaw movements.

Core Concepts

Zero Lag: Uses a specialized IIR filter chain to smooth the data without introducing significant delay.
Noise Reduction: Filters out high-frequency noise while retaining the underlying trend.
Bounded Range: Output is strictly bounded between 0 and 100, similar to RSI.
Smoothness: Produces a clean, continuous curve suitable for precise peak/valley detection.

Parameters

Parameter	Type	Default	Description
Period	int	14	The smoothing period (typically 8-40).

Formula

RSX uses a cascading filter structure. The smoothing factor \alpha is derived from the period:

\alpha = \frac{3}{Period + 2}

The algorithm processes price changes (v_8) through multiple smoothing stages for both the raw momentum and its absolute value. The final RSX is calculated as:

RSX = \left( \frac{v_{14}}{v_{20}} + 1 \right) \times 50

Where v_{14} is the smoothed momentum and v_{20} is the smoothed absolute momentum.

C# Implementation

Standard Usage

using QuanTAlib;

var rsx = new Rsx(14);
var result = rsx.Update(new TValue(DateTime.UtcNow, price));
Console.WriteLine($"RSX: {result.Value}");

Span API (High Performance)

double[] prices = { ... };
double[] results = new double[prices.Length];

Rsx.Calculate(prices, results, 14);

Chaining

var rsx = new Rsx(14);
var sma = new Sma(rsx, 3); // Smooth the RSX further

Interpretation

Overbought/Oversold: Values above 70 (or 80) indicate overbought conditions, while values below 30 (or 20) indicate oversold conditions.
Trend Confirmation: RSX crossing 50 can signal a trend change.
Divergence: Divergence between price and RSX often precedes a reversal.
Smoothness: Due to its smoothness, RSX slope changes are more significant than RSI slope changes.

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