Hi, I am trying to use fSeries library form CRAN, especialy the armaFit function. armaFit(formula = x ~ arima(2, 0, 1), method = c("CSS-ML", "ML", "CSS", "yw", "burg", "ols", "mle"), include.mean = TRUE, fixed = NULL, fracdiff.M = 100, fracdiff.h = -1, title = "", description = "", ...) The problem that I faced is that an argument of this function (the x) is an object of class fARMA returned by the fitting function armaFit. At the first time that the regrssion will be made this objected has not been returned yet, so, how could I use it? x is not the numerical vector with the data set, as it is in the arma function from tseries library. [[alternative HTML version deleted]]