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function [A,B,C,D] = ss(Hd) %SS Discrete-time filter to state-space conversion. % [A,B,C,D] = SS(Hd) converts discrete-time filter Hd to state-space % representation given by % x(k+1) = A*x(k) + B*u(k) % y(k) = C*x(k) + D*u(k) % where x is the state vector, u is the input vector, and y is the output % vector. % % See also DFILT. % Author(s): R. Losada % Copyright 1988-2002 The MathWorks, Inc. % Construct a df1t object; den is always 1 df1tobj = dfilt.df1t(Hd.Numerator,1); % Get it's state-space representation [A,B,C,D] = ss(df1tobj);