Defines the method that will be used when calling Simulate on the tsModel-class.
The passed Simulate function must have exactly the following three arguments: n (numeric),
spec (a list) and par (another list). It returns a numeric vector with the
simulated data.
# S4 method for tsModel
setSimulate(object, Simulate)the tsModel-class for that the estimation method shall be defined
a function that has exactly three argumens: n (numeric),
spec (a list) and par (another list).
Nothing, it sets the sim_function slot of the tsModel-class.