In one of the application of Bollinger Bands, one can use double bottom ( W shape bottom) as buy signal, by using percent b. I wonder how to formulate this buy signal?


percent b chart

1
1_neckline__ 1 <---breakthrough neckline (buy)
1 1 1
1 1 1 <---- higher low
1 <--- lower low

I want the indicator can identify the lower low, higher low, neckline position, and the buy signal, within let's say 10 days.

Can anyone help? Thanks a lot!

Thomas