display_pz.m

离散控制系统设计的MATLAB 代码

function  display_pz(S)
%  displays poles & zeros as two column array
%
%  syntax:   display_pz(S)
%
%  input:  S  is any ss-system in packed form
%  output: PZ is an N x 2 array, with poles in first column
%		and zeros + NaNs as required in 2nd column

%%%%%%%%%%%%%%%%% display_pz.m %%%%%%%%%%%%%%%%%%
%   Discrete-Time Control Problems using        %
%       MATLAB and the Control System Toolbox   %
%   by J.H. Chow, D.K. Frederick, & N.W. Chbat  %
%         Brooks/Cole Publishing Company        %
%                September 2002                 %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%---- find poles and sort by real part, rightmost first
pp = eig(unpack_ss(S,'a'));
[ppp,ii] = sort(real(pp));
poles_S = pp(ii(length(ii):-1:1));

%---- find zeros and sort by real part, rightmost first
zz = tzero(S);
[zzz,ii] = sort(real(zz));
zeros_S = zz(ii(length(ii):-1:1));

pz = [poles_S  Inf*ones(length(pp),1)...
		  [zeros_S;  NaN*ones(length(pp)-length(zz),1)]];

disp(' ')
disp('    Poles                                  Zeros')
disp('----------------------------------------------------')
disp(pz)

if  poles_S(1) > 0,
	disp(' ')
	disp('**** RHP pole ==> unstable system ****')
end
%%%%%%%%%%