[R] Problem about SARMA model forcasting

Hello, Guys: I'm from China, my English is poor and I'm new to R. The first message I sent to R help meets some problems, so I send again. Hope that I can get useful suggestions from you warm-hearted guys. Thanks. I builded a multiplicative seasonal ARMA model to a series named "cDownRange". And

[R] Is the SARMA forcasting formula correct?

Hello, Guys: I'm from China, my English is poor and I'm new to R. This is my first time to use R-help. Hope that I can get useful suggestions from you warm-hearted guys. Thanks. I builded a multiplicative seasonal ARMA model to a series named "cDownRange". And the order is (1,1)*(0,1)45 I fitte