error while using iddata

Hi i wrote the code below but when i run it i face two errors that i dont get it can anyone help me

Error using iddata/numArgumentsFromSubscript (line 8) The syntax "Data{...}" is not supported. Use the "getexp" command to extract individual experiments from an IDDATA object.

Error in arma (line 29)

plot(t,yhat1{1}.y,'--',t,y);

I have this two erros please help me

Thanks

%% Generate the data
N = 250; 
Ts = 1; 
u_var = 1; 
noise_var = 1;
a = [1 -1.5 0.7]; 
b = [0 1 .5]; c = [1 -1 0.2];
u = sign(randn(2*N,1))*sqrt(u_var); 
v = randn(2*N,1);
M = idpoly(a,b,c,1,1,noise_var,Ts);
y = sim(M,[u v]);
uv = u(N+1:end); 
vv = v(N+1:end); 
yv = y(N+1:end);
u = u(1:N); 
v = v(1:N); 
y = y(1:N);
DATe = iddata(y,u,Ts); DATv = iddata(yv,uv,Ts);
DATe1 = get(DATe);   DATv1= get(DATv)
%% Identification
na = 2; nb = 2; nc = 2;
theta_pem = armax(DATe,[na nb nc 1]); % ARMAX using PEM
%% Compare the measured output and the model output
[yhat1,fit1] = compare(DATe,theta_pem);
[yhat2,fit2] = compare(DATv,theta_pem);
t = 1:N;
figure;
subplot(2,1,1);
plot(t,yhat1{1}.y,'--',t,y);
legend('model','measured');
title('Comparison on estimation data set','FontSize',16);
ylabel('y');xlabel('t');
subplot(2,1,2);
plot(t,yhat2{1}.y,'--',t,yv);
legend('y2','y');
legend('model','measured');
title('Comparison on validation data set','FontSize',16);
ylabel('y');xlabel('t');

Answer 1

[Walter Roberson]

Is there a reason you are not using

plot(yhat1)

??

But if you insist...

plot(t, getexp(yhat1,1).y, '--', t, y);

[arash rad]

thanks for answering but when i use this error below occured :

Undefined variable "getexp" or class "getexp".

what should i do?

[Walter Roberson]

Please try this code and see what you get.

%% Generate the data
N = 250; 
Ts = 1; 
u_var = 1; 
noise_var = 1;
a = [1 -1.5 0.7]; 
b = [0 1 .5]; c = [1 -1 0.2];
u = sign(randn(2*N,1))*sqrt(u_var); 
v = randn(2*N,1);
M = idpoly(a,b,c,1,1,noise_var,Ts);
y = sim(M,[u v]);
uv = u(N+1:end); 
vv = v(N+1:end); 
yv = y(N+1:end);
u = u(1:N); 
v = v(1:N); 
y = y(1:N);
DATe = iddata(y,u,Ts); DATv = iddata(yv,uv,Ts);
DATe1 = get(DATe);   DATv1= get(DATv)

DATv1 = struct with fields:
              Domain: 'Time'
                Name: ''
          OutputData: {[250×1 double]}
          OutputName: {'y1'}
          OutputUnit: {''}
           InputData: {[250×1 double]}
           InputName: {'u1'}
           InputUnit: {''}
              Period: {[Inf]}
         InterSample: {'zoh'}
                  Ts: {[1]}
              Tstart: {[]}
    SamplingInstants: {[250×0 double]}
            TimeUnit: 'seconds'
      ExperimentName: {'Exp1'}
               Notes: {}
            UserData: []

%% Identification
na = 2; nb = 2; nc = 2;
theta_pem = armax(DATe,[na nb nc 1]); % ARMAX using PEM
%% Compare the measured output and the model output
[yhat1,fit1] = compare(DATe,theta_pem);
[yhat2,fit2] = compare(DATv,theta_pem);
t = 1:N;
figure;
subplot(2,1,1);
plot(t, getexp(yhat1,1).y, '--', t, y);
legend('model','measured');
title('Comparison on estimation data set','FontSize',16);
ylabel('y');xlabel('t');
subplot(2,1,2);
plot(t, getexp(yhat2,1).y, '--', t, yv);
legend('y2','y');
legend('model','measured');
title('Comparison on validation data set','FontSize',16);
ylabel('y');xlabel('t');

[arash rad]

thank you very much