function srt03Nyquist2
% SRT Rechnerdemo 3
% WS 2000-2001
% Klaus Schmid, 23.10.2000 / Eberhard Münz 28.11.2001
warning off;
n=[1 1];
p=[0 -1 2];
k=evalin('base','k');
k=-k;
% Übertragungsfunktion berechnen
System = zpk(n,p,k)
re=[];
im=[];
for w=0:0.03:20
nenner=1;
zaehler=k;
for m=1: length(p)
nenner=(i*w-p(m))*nenner;
end
for m=1:length(n)
zaehler=(i*w-n(m))*zaehler;
end
re=[re;real(zaehler/nenner)];
im=[im;imag(zaehler/nenner)];
end
if isempty(findobj('tag','srt03nyquist0'))
fig=figure;
set (fig,'tag','srt03nyquist0','Name',['Nyquist-Ortskurve für k=' num2str(k)]);
else
figure(findobj('tag','srt03nyquist0'));
end
%plot([-2;2],[0; 0],'gr');
%hold on;
%plot([0; 0],[-2; 2],'gr');
%hold on;
plot(re,im,'b');
hold on;
plot(-1,0,'+r','Linewidth',2);
hold on;
plot(-1.5,0,'w');
%axes;
grid on;
hold off;