//@version=4
study(title="51bitquant_keltner_channel", shorttitle="keltner_channel", overlay=true)
period = input(defval=30, minval=10, title="period")
atr_dev = input(defval=3, minval=1, title="atr_dev")
sma_value = sma(close, period)
tr_value1 = max(high - low, abs(high - close[1]))
tr_value = max(abs(low - close[1]), tr_value1)
atr_value = sma(tr_value, period)
keltner_up = sma_value + atr_dev * atr_value
keltner_down = sma_value - atr_dev * atr_value
plot(keltner_up, color=color.green, linewidth=3)
plot(sma_value, color=color.red, linewidth=3)
plot(keltner_down, color=color.green, linewidth=3)