c_ses_2.gif

c=.2 default, or else c is input into the trend "find S_1...S_K," where S_1=y_1. Then S_{i+1}= a_i * S_i + (1-a_i) y_i. For i=1,...,K -1. Then Y{forecast}(x) = a * S_K + (1-a)*y_K. Where a_i=(1-c)^x_{i+1}^{-x_i}, and a=(1-c)^ {x-x}_K. Note: when Xlist is missing, x_{i+1}-x_i=1, and the corresponding coefficients a_i=(1-c) for i=1. ...,K-1.