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function [A,B,C,D] = ss(Hd) %#ok<STOUT,INUSD> %SS Discrete-time filter to state-space conversion (not supported). % dfilt.allpass does not support the analysis method ss. % For other dfilt objects, ss works as follows: % [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. % Copyright 2013-2014 The MathWorks, Inc. % Return error message 'Method ss not supported by dfilt.allpass filters.' error(message('signal:dfilt:allpass:allpass:noStateSpaceSupport'))