High Low Envelope Sigma

//@version=2

study(title = "High Low Envelope Sigma", shorttitle = "HLE Sigma", overlay = true)

// Revision:        1
// Author:          @JayRogers
//
// *** USE AT YOUR OWN RISK ***
// 
// Description:
// - High and Low Envelope channel with median line and 'sigma' offsets to try and encapsulate
//   price flow and quickly locate likely areas of support and resistance within smaller trend.

//=== INPUTS ===
length  = input(defval = 25, title = "Envelope Length", minval = 1, maxval = 1000)
sigma   = input(defval = 1.0, title = "Sigma Multiply", minval = 0.01, step = 0.1)
//=== /INPUTS ===

//=== SERIES and VAR ===
upperEnvelope   = highest(high, length)
lowerEnvelope   = lowest(low, length)
envelopeMedian  = (upperEnvelope + lowerEnvelope) / 2
envelopeSigma   = ((upperEnvelope - lowerEnvelope) / 8) * sigma
//=== /SERIES and VAR ===

//=== PLOTTING ===
plot(upperEnvelope, title = "Upper Envelope", color = #66FFFF, linewidth = 2)
plot(envelopeMedian + envelopeSigma, title = "Upper Sigma", color = #66FFFF, linewidth = 1, style = line)
plot(envelopeMedian, title = "Median", color = silver, linewidth = 1, style = circles)
plot(envelopeMedian - envelopeSigma, title = "Lower Sigma", color = #FF1133, linewidth = 1, style = line)
plot(lowerEnvelope, title = "Lower Envelope", color = #FF1133, linewidth = 2)
//=== /PLOTTING ===