MATLAB: I can solve this error

undefined function

Mdl = arima('Constant',0,'D',1,'Seasonality',12,...
    'MALags',1,'SMALags',12);
EstMdl = estimate(Mdl,y);

There is this error:

I do have this function available, it is part of the econometrics toolbox

The output is robust to outliers and are not heteroskedasticity consistent estimates.

If that is what you are interested in, please check out the HAC command in the Econometrics Toolbox:

The help section of the forecast() function shows that there are two inputs and then you can enter optional parameter-value pairs.

help forecast
% [Y,YMSE,V] = forecast(Mdl, numPeriods, param1,val1,param2,val2,...)

If you're checking the predictive performance of the model, the paramter name you might be missing is 'Y0'.

[yF,yMSE] = forecast(EstMdl,60,'Y0',y);
%                               **

But check the other name-value pairs to be sure about what you're specifying here.

Recent version of matlab:

Older versions of matlab