www.gusucode.com > signal 工具箱matlab源码程序 > signal/@dfilt/@singleton/zpk.m
function [z,p,k] = zpk(Hd) %ZPK Discrete-time filter zero-pole-gain conversion. % [Z,P,K] = ZPK(Hd) returns the zeros, poles, and gain corresponding to the % discrete-time filter Hd in vectors Z, P, and scalar K respectively. % % Example: % [b,a] = butter(3,.4); % Hd = dfilt.df2t(b,a); % [z,p,k] = zpk(Hd) % % % See also DFILT. % Author: Thomas A. Bryan % Copyright 1988-2006 The MathWorks, Inc. if ~isequal(size(Hd),[1,1]), error(message('signal:dfilt:singleton:zpk:InvalidDimensions')); end [b,a] = tf(Hd); [z,p,k] = tf2zpk(b,a);