Whenever I run a code to simulate AR/ARMA/SARIMA process using command:
(say)

*m1=(arima(z, order = c(1, 0, 1), seasonal = list(order = c(0, 0, 0),
period = NA),xreg = NULL, include.mean = FALSE, transform.pars = FALSE,
fixed = NULL,init = NULL))*

Even for moderately large values of phi (the AR part) it returns back the
error1 and stops the simulation process.

*Error#1:*

*Error in stats:::arima(x = x, order = order, seasonal = seasonal, xreg =
xreg,  :   non-stationary AR part from CSS*

*In addition: Warning message:*

*In `[<-.factor`(`*tmp*`, ri, value = NA_integer_) :  invalid factor level,
NAs generated*



*Error#2:*

*Error in optim(init[mask], armafn, method = optim.method, hessian = TRUE,
:    non-finite finite-difference value [1]*





What I have noted is that if we adopt the ML method it will forcefully make
the process to attain stationarity. And on doing so the error#1 is no more
there but now I see error#2  and this new message keeps on intervening all
the time and I am not able to run more than 7 iterations Can you please
help me in getting rid of it

Thanks a million

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