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Force Index(1) = {Close (current period)  –  Close (prior period)} x Volume =gain +/- I call it FI out value
FI (20) = 20 - period EMA of Force Index(1)
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Twin Evil indicator=first line blue color
100− [ 1+ −((Previous Average Loss FI ×20) + Current Loss)
(Previous Average Gain FI ×20) + Current Gain /100 ] = output value (0-100)
Second line Red color on previous output data
100− [ 1+ −((Previous Average Loss ×20) + Current Loss)
(Previous Average Gain FI ×20) + Current Gain /100 ] = output value (0-100)

Adding standard deviation calculation
BOLU=MA(TP,n)+m∗σ[TP,n]
BOLD=MA(TP,n)−m∗σ[TP,n]
where:
BOLU=Upper Bollinger Band
BOLD=Lower Bollinger Band
MA=Moving average
TP (typical price)=(High+Low+Close)÷3
n=Number of period (here put 21 then repeat the process with 40 ) in smoothing period (typically 20)
m=Number of standard deviations (typically 1.5)
σ[TP,n]=Standard Deviation over last n periods of TP