MATLAB: How to make a code continue running if while loop returns NaN

Question

I have the following code below

 R =5; % LQR Weighting
 Q = [100 0 0 0; 0 5 0 0; 0 0 10 0; 0 0 0 1];
 K = dlqr(Adhat,Bdhat,Q, R);
 R1a = tf(ss(Adhat,Bdhat,K,0));
 T1a = minreal(minreal(R1a)/(1 + minreal(R1a))); % Closed Loop   Transfer Function
 figure(1)
 step(T1a)
 S = stepinfo(T1a,'SettlingTimeThreshold',0.01); %Settling time threshold specification for 1%
 x = S.SettlingTime;
 while x > 0.1
   R=R/2;
   Q = Q*2;
   K = dlqr(Adhat,Bdhat,Q, R);
    R1a = tf(ss(Adhat,Bdhat,K,0));
    T1a = minreal(minreal(R1a)/(1 + minreal(R1a)));
    figure(1)
    step(T1a)
    hold on
    x1 = 0:0.1:20; y1 = 1.01*ones(size(x1)); line(x1,y1) % Line to indicate +1%
    x2 = 0:0.1:20; y2 = 0.99*ones(size(x2)); line(x2,y2) % Line to indicate -1%
    hold off
    S = stepinfo(T1a,'SettlingTimeThreshold',0.01); %Settling time threshol specification for 1%
    x = S.SettlingTime;
 end
 figure(2)
 nyquist(R1a)
 title('Nyquist diagram of return ratio, K ')
 hold on
 circ = -1 +exp(j*[0:pi/1000:2*pi]');
 plot(circ,'r')
 hold off
 disp('See Fig 2')
 disp(['Settling Time= ' num2str(x)])
 disp(['R= ' num2str(R)])
 disp(['K= ' num2str(K)])

I need the code to continue running even if the while loop returns a NaN value, I cant seem to get this to work. I have tried using if else loop and it returns the same result.

I will apprciate any tips to get this issue resolved.

Thanks

Answer 1

I have only a faint idea of what your problem might be. Perhaps this helps:

while (x > 0.1) || isnan(x)