Average True Range Overlay

Plots ATR calculated on a daily basis as an overlay on the current chart.

Implemented using the builtin atr function.

ATR is a volatility indicator
originally developed by J. Welles Wilder, Jr. for commodities:
New Concepts in Technical Trading Systems. Greensboro, NC: Trend Research. ISBN 978-0-89459-027-6.

The range of a day's trading is simply R = high − low.
The true range extends it to yesterday's closing price if it was outside of today's range:
TR = max[(high-low), abs(high-close(previous)), abs(low - close(previous))]

The average true range is an N-day smoothed moving average of the TR values.

A first stab at a sensible stop loss level might be 3*ATR below recent peak.