R : 시계열 관련 함수

1. Arima : ARIMA 모형 추정을 위한 함수
      arima(x, order = c(0, 0, 0),
                    seasonal = list(order = c(0, 0, 0), period = NA),
                    xreg = NULL, include.mean = TRUE,
                    transform.pars = TRUE,
                    fixed = NULL, init = NULL,
                    method = c("CSS-ML", "ML", "CSS"),
                    n.cond, optim.method = "BFGS",
                    optim.control = list(), kappa = 1e6)

2. ACF, PACF
       acf(x, lag.max = NULL, type = c("correlation", "covariance", "partial"),
                    plot = TRUE, na.action = na.fail, demean = TRUE, ...)

       pacf(x, lag.max, plot, na.action, ...)

3. ADF.TEST{tseries}
       adf.test(x, alternative = c("stationary", "explosive"), k = trunc((length(x)-1)^(1/3)))