Index exceeds the number of array elements(3)

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

[Andrew Newell]

Can you provide the code for ?

[Andrew Newell]

And when does the error message occur?

Answer 1

[Cris LaPierre]

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).