Whittaker Envelope

The Whittaker Envelope fits a smooth, non-linear envelope around price using Whittaker–Eilers smoothing combined with asymmetric least squares (ALS). Instead of offsetting a moving average, it solves for three curves over the last N bars: an upper band weighted toward peaks, a lower band weighted toward troughs, and a midline tracing the structural path between them. Because the fit is recomputed over the window as new bars arrive, the envelope repaints — a research tool, not a real-time signal generator.

How to Trade the Whittaker Envelope?

• Widening envelope: growing distance between the bands signals expanding volatility and stronger directional movement.
• Narrowing envelope: compression points to consolidation or range-bound conditions.
• Midline direction: a rising midline frames a bullish structural bias, a falling one bearish pressure.
• Extrapolated slope: the projection extends the bands' trajectory forward — a reference against live action, not a prediction.

Under the hood sits a penalized fit from the family of the Whittaker–Henderson smoother; ALS asymmetry pushes each band toward one side of price, so no standard-deviation multiplier is needed.

Whittaker Envelope Settings

• Length: bars in the calculation window — shorter is more reactive, longer gives broader structure.
• Lambda (λ): smoothing intensity; higher values produce stiffer, straighter bands.
• Lower Asymmetry (p): how strongly the lower band hugs troughs — typically very low (e.g. 0.001).
• Upper Asymmetry (p): how strongly the upper band tracks peaks — typically very high (e.g. 0.999).
• Iterations: ALS refinement passes; more passes fit tighter at extra computational cost.
• Extrapolation: how many bars of slope projection to draw.
• Source (default Close): the price series being fitted.

Frequently Asked Questions

Does the Whittaker Envelope repaint?

Yes, by design. The curve is optimized over a fixed historical window, so the entire envelope can adjust as new data enters the calculation. Treat it as a lens for volatility regimes, and pair live decisions with non-repainting confirmation.

How does it compare to the Nadaraya-Watson Envelope?

Both wrap price in smoothing-based bands. The Nadaraya-Watson Envelope forms around a kernel-weighted estimate, while this build solves an asymmetric penalized fit whose bands independently chase peaks and troughs.

Where can I get this indicator?

The Whittaker Envelope is a free release in the LuxAlgo Library. Load it onto a chart from this page — or into Quant, LuxAlgo's AI, to study its behavior across markets and window lengths.