Generally speaking, Boolean channel lines are composed of upper, middle and lower trajectory lines, but if the switch parameter is set to 1, the graph is represented by four lines. Among them, the upper rail and the lower rail are located at the outermost side of the channel, which are the pressure line (rising line) and the support line (falling line) of this trend respectively; The middle one, the middle rail, is the average price line. In most cases, the price always runs in a strip-shaped interval composed of upper and lower tracks, and the position of the track automatically adjusts with the change of the price. The width of the band can show the range of price change, and the wider the band, the greater the price change.

Calculation formula:

1. calculate MA

MA= cumulative closing price of recent n periods /N periods.

Computational MD

MD= square root (latest cumulative n periods (closing price -MA)* (closing price -MA)/N)

3. calculate MB, UP, DN.

MB=I- 1 ma

Up =MB+2*MD

DN=MB-2*MD