Holt's Linear Model (Additive): $$L_t = \alpha Y_t + (1 - \alpha)(\ L_{t-1} + b_{t-1})$$ $$b_t = \beta (L_t - L_{t-1}) + (1 - \beta ) b_{t-1}$$ $$F_t = L_t + b_t m$$

Initialize: \( b_1 = Y_2 - Y_1 \, , \quad L_1 = Y_1 \)