//@version=4
study(title="51bitquant_channel", shorttitle="channel", overlay=true)

period = input(defval=20, minval=5, title="period")
dev =  input(defval=2.0, minval=1.0, title="dev")

sma_value = sma(hlc3, period) //移动平均线即指简单移动平均线(SMA)
std_value = stdev(hlc3, period)

up = sma_value + dev * std_value
down = sma_value - dev * std_value

plot(up, color=color.red, linewidth=3)
plot(sma_value, color=color.green, linewidth=3)
plot(down, color=color.red, linewidth=3)