Error: Index exceeds the number of array elements. Index must not exceed 1.

7 次查看（过去 30 天）
Aliya Magno
Aliya Magno 2024-10-18
评论： Aliya Magno 2024-10-19
Ran in:
Hello, I am trying to build a code that identifies a system using recursive least squares and i created an function based on the theory
function[thetak,Pk]=real_time_identification_try2(u,y,Pk_1,thetak_1,alphak)
%function determines theta and the covariance
%u= data input
%y=data output
%n number of zeros
%m number of poles
%alpha = forgetting factor
%vector a_k(vector with inputs and outputs)
a_k=[u, -y];
%implementation
thetak= thetak_1+((Pk_1* a_k.')/((1/alphak)+a_k*Pk_1*a_k.'))*(y(k-a_k*thetak_1));
Pk = Pk_1 -((Pk_1*a_k.'*a_k*Pk_1)/((1/alphak)*a_k*Pk_1*a_k.'));
end
And am calling the function in this script
clc
clear
load linearidade2.mat
u=simout.Data(:,1);
y=simout.Data(:,2);
N = length(u);
%poles and zeros
n= 2;
m= 0;
alphak=0.99;
%setup covariance and theta
P0=100*eye(n+m+1);
theta0 = 0;
%incial conditions
Pk = P0;
thetak = theta0;
for k= max(n,m)+1: N
%input data
u=(k:-1:k-m);
y=(k-1:-1:k-n);
% past inputs
for j = 0:m+1
if k-j > 0
a_k(j+1) = u(k-j); % Insert u(k), u(k-1), ..., u(k-m) em a_k
end
end
% past outputs
for j=1:n
if k-j > 0
a_k(m+j+1) = -y(k-j); %insert y(k),y(k-1),...,y(k-n) em a_k
end
end
[thetak,Pk] = real_time_identification_try2(u, y,Pk,thetak, alphak);
end
Index exceeds the number of array elements. Index must not exceed 1.
% % updating the covariance matix for k+1
for j=0:m+n
if k-j > 0;
P = Pk;
theta = thetak;
end
end
[thetak,Pk]=real_time_identification_try2(u,y,Pk_1,thetak_1,alphak)
% Create the transfer function with estimated parameters
G_estimated = tf([theta(1:1:m+1)], [1 theta(m+2:1:n+m+1)], 0.010);
disp('Estimated Transfer Function:');
G_estimated
% Display final estimated parameters
disp('Final estimated parameters:');
disp(theta);
Thank you in advance
  4 个评论
显示 2更早的评论
DGM
DGM 2024-10-18
编辑：DGM 2024-10-18
You initialize u and y from the matfile
u=simout.Data(:,1);
y=simout.Data(:,2);
but then you overwrite the data with some indices
%input data
u=(k:-1:k-m);
y=(k-1:-1:k-n);
There's also a code analyzer warning on this line:
Pk = Pk_1 -((Pk_1*a_k.'*a_k*Pk_1)/((1/alphak)*a_k*Pk_1*a_k.'));
Parenthesize the multiplication of a_k with its transpose to ensure the result is Hermetian
I don't think that's what's causing your indexing error, but you should double check that it's not causing any issues for your intended purpose.

请先登录，再进行评论。

请先登录，再回答此问题。

回答（1 个）

Cris LaPierre
Cris LaPierre 2024-10-18
Ran in:
When the first for loop starts, your variables have the following values
  • k = 3
  • j = 0
  • m = 0
  • n = 2
So the value of u is u=(k:-1:k-m) which is 3. Then inside the look that defines a_k, you index u using u(k-j), which is u(3). But u is a scalar (one element). Here is code that recreates the error.
u=3;
u(3)
Index exceeds the number of array elements. Index must not exceed 1.

类别

在 Help Center 和 File Exchange 中查找有关 Linear Model Identification 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by