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function n = thisnstates(Hd) %NSTATES Number of states in discrete-time filter. % NSTATES(Hd) returns the number of states in the % discrete-time filter Hd. The number of states depends on the filter % structure and the coefficients. % Author: Thomas A. Bryan % Copyright 1988-2004 The MathWorks, Inc. if isempty(Hd.A), n = 0; else n = size(Hd.A,1); end