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    %% Nonmodifiable Properties
% Not all model properties are modifiable. You cannot change these
% properties in an existing model:
%
% * |P|. This property updates automatically when the lag corresponding to
% the largest nonzero GARCH term changes.
% * |Q|. This property updates automatically when the lag corresponding to
% the largest nonzero ARCH or leverage term changes.
%%
% Not all name-value pair arguments you can use for model creation are
% properties of the created model. Specifically, you can specify the
% arguments |GARCHLags| and |ARCHLags| (and |LeverageLags| for EGARCH and
% GJR models) during model creation. These are not, however, properties of
% |garch|, |egarch|, or |gjr| model. This means you cannot retrieve or
% modify them in an existing model.
%%
% The ARCH, GARCH, and leverage lags update automatically if you add any
% elements to (or remove from) the coefficient cell arrays |GARCH|, |ARCH|,
% or |Leverage|.
%%
% For example, specify an EGARCH(1,1) model:

% Copyright 2015 The MathWorks, Inc.

Mdl = egarch(1,1)
%%
% The model output shows nonzero GARCH, ARCH, and leverage coefficients at
% lag 1.
%%
% Add a new GARCH coefficient at lag 3:
Mdl.GARCH{3} = NaN
%%
% The nonzero GARCH coefficients at lags 1 and 3 now display in the model
% output. However, the cell array assigned to |GARCH| returns three
% elements:
garchCoefficients = Mdl.GARCH
%%
% |GARCH| has a zero coefficient at lag 2 to maintain consistency with
% traditional MATLAB(R) cell array indexing.