Index exceeds the number of array elements(3)

Question

Danielle sal 2021-4-16

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/804296-index-exceeds-the-number-of-array-elements-3

评论： Andrew Newell 2021-4-16

For a matrix

A=[4 1 3 1;1 4 1 3;3 1 4 1;1 3 1 4]
[L,P,D]=eigen(A);

I have a function:

function [L,P,D]=eigen(A)
format
[~,n]=size(A);
P=[];
D=[];
L=eig(A);
L=transpose(L);
L=real(L);
L=sort(L);
for i= 1:n-1
    Temp1 = L(i);
    Temp2 = L(i+1);
    if closetozeroroundoff(Temp1-Temp2, 7)== 0
        L(1,i+1) = L(1, i);
    end 
end
if rank(L) ~= n
    L = closetozeroroundoff(L,7);
end
fprintf('all eigenvalues of A are\n')
display(L)
M = unique(L);
M = transpose(M);
display(M)
m = groupcounts(transpose(L));
display(m)
for i = 1:n
    fprintf('eigenvalue %d has multiplicity %i\n',M(i),m(i))
end

and I get the error that Index exceeds the number of array elements(3) even though it prints each eigenvalue with its multiplicity. Any ideas on how to fix it?

M is the eigenvalues that are unique

L is the list of all the eigenvalues (even the repeated ones)

m is the number of times each value in L appears in M

2 个评论
显示无隐藏无

Andrew Newell 2021-4-16

Can you provide the code for

?

Andrew Newell 2021-4-16

And when does the error message occur?

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Cris LaPierre 2021-4-16

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/804296-index-exceeds-the-number-of-array-elements-3#answer_677201

在 MATLAB Online 中打开

We can't run your code. We need your closetozeroroundoff function.

However, the error message isn't about whether or not there are 3 eigen values. It is that you are trying to index a variable that only has 3 values with an index that is greater than 3.

% Create an array with 3 elements
num = [1,2,3];
% Works
num(2)
ans = 2
% Error because 5>length(num)
num(5)
Index exceeds the number of array elements (3).