The NumberOfParameters command returns the number of fixed or optimizable parameters that occur in model.

This includes the initial values for states such as ${\mathrm{\ell }}_t$ and, if applicable, $b_t$ and $s_t$, but it does not include $\mathrm{\sigma }$ or, for example, $\mathrm{period}$ or $\mathrm{trend}$. It also doesn't include parameters that don't actually occur in the model; for example, $\mathrm{\beta }$ does not occur in an $\left(A\,N\,N\right)$ model. (Commands such as GetParameters will still return these parameters, but they are set to their default value.)

If a model is not specialized (see the Specialize command), then its number of parameters is not yet determined. In that case, NumberOfParameters will return $\mathrm{undefined}$.

$\mathrm{with}\left(\mathrm{TimeSeriesAnalysis}\right)\:$

$\mathrm{NumberOfParameters}\left(\mathrm{ExponentialSmoothingModel}\left(A\,N\,N\right)\right)$

$2$

$\mathrm{model}≔\mathrm{ExponentialSmoothingModel}\left(A\,N\,A\right)\:$

$\mathrm{NumberOfParameters}\left(\mathrm{model}\right)$

$\mathrm{undefined}$

$\mathrm{SetParameter}\left(\mathrm{model}\,\mathrm{period}=12\right)$

$\mathrm{NumberOfParameters}\left(\mathrm{model}\right)$

$14$

Hyndman, R.J. and Athanasopoulos, G. (2013) Forecasting: principles and practice. http://otexts.org/fpp/. Accessed on 2013-10-09.

Hyndman, R.J., Koehler, A.B., Ord, J.K., and Snyder, R.D. (2008) Forecasting with Exponential Smoothing: The State Space Approach. Springer Series in Statistics. Springer-Verlag Berlin Heidelberg.

The TimeSeriesAnalysis[NumberOfParameters] command was introduced in Maple 18.

For more information on Maple 18 changes, see Updates in Maple 18.