Bollinger Bands with three standard deviations
study(title = "Triple Bollinger Bands", shorttitle="Triple BB", overlay=true) source = close length = input(20, minval=20, maxval=50) stdDev1 = input(1.0, minval=1.0, maxval=1.3) stdDev2 = input(2.0, minval=2.0, maxval=2.3) stdDev3 = input(3.0, minval=3.0, maxval=3.3) basis = sma(source, length) dev1 = stdDev1 * stdev(source, length) dev2 = stdDev2 * stdev(source, length) dev3 = stdDev3 * stdev(source, length) upper1 = basis + dev1 lower1 = basis - dev1 upper2 = basis + dev2 lower2 = basis - dev2 upper3 = basis + dev3 lower3 = basis - dev3 plot(basis, color=yellow) p1 = plot(upper1, color=blue) p2 = plot(lower1, color=blue) p3 = plot(upper2, color=aqua) p4 = plot(lower2, color=aqua) p5 = plot(upper3, color=red) p6 = plot(lower3, color=red)