Calculate: P =
Set: Lt = P, bt = 0, St = Yt/P, for t = 1 to s
For the remaining periods, use the following formulas:
α—Alpha
β—Beta
γ—Gamma
m—Number of periods ahead to forecast
s—Length of the seasonality
Lt—Level of the series at time t
bt—Trend of the series at time t
St—Seasonal component at time t
Note: | First fit is available from period (s + 1) |