Standard Deviation Script

// Standard Deviation from Open Price  //
study(title="StdDev", shorttitle="StdDev", overlay = true )

Length = input(defval = 288, title="Lookback Period........................................................ *Note: Standard Deviation tends to increase commensurate to lookback period*")
Basis = input(type=source, defval=open, title="Source")

sd1 = input(1 , title="X Standard Deviation (Default 1)")
sd2 = input(2 , title="X Standard Deviation (Default 2)")
sd3 = input(3 , title="X Standard Deviation (Default 3)")

// Standard Deviation will fall on a bell curve with .5 of it on the right of the mean and .5 of it on the left of mean
// That's what these do
ssd1 = sd1 / 2
ssd2 = sd2 / 2
ssd3 = sd3 / 2

sd = stdev(Basis, Length)

z1 = Basis + (ssd3 * sd)
z2 = Basis + (ssd2 * sd)
z3 = Basis + (ssd1 * sd)
z4 = Basis - (ssd1 * sd)
z5 = Basis - (ssd2 * sd)
z6 = Basis - (ssd3 * sd)

// SD plot//
plot(z1, linewidth=2, style=circles, color=green, offset=0, title="+3 sd")
plot(z2, linewidth=2, style=circles, color=blue, offset=0, title="+2 sd")
plot(z3, linewidth=2, style=circles, color=red, offset=0, join=true, title="+1 sd")
plot(z4, linewidth=2, style=circles, color=red, offset=0, join=true, title="-1 sd")
plot(z5, linewidth=2, style=circles, color=blue, offset=0, title="-2 sd")
plot(z6, linewidth=2, style=circles, color=green, offset=0, title="-3 sd")