narsimul
========

armax simulation ( using rtitr)



Calling Sequence
~~~~~~~~~~~~~~~~


::

    [z]=narsimul(a,b,d,sig,u,[up,yp,ep])
    [z]=narsimul(ar,u,[up,yp,ep])




Description
~~~~~~~~~~~

ARMAX simulation. Same as arsimul but the method is different the
simulation is made with rtitr