I have built an ARIMA model in R with the "forecast" package's
auto.arima() function. I want to simulate the ARIMA model with the same starting values as the original time series. For example, if my original time series has values from time 0 to time 2000, I want the ARIMA model to simulate the same time period (0 to 2000). If the ARIMA model is ARIMA(5,0,1), I want the values from time 0 to time 4 to be retained in the ARIMA model and the model simulates from that point on using those first 5 points.
I appreciate your help!