how to change the diagonal of a matrix 3x3 with a vector with 3 elements in matlab

To change the diagonal of a 3x3 matrix with a vector of 3 elements in MATLAB, you can use indexing and diagonalization.

Here's an example code snippet:

main.m
% create a 3x3 matrix
A = [1 2 3; 4 5 6; 7 8 9]

% create a vector with 3 elements
v = [10 11 12]

% diagonalize the vector to a 3x3 matrix
V = diag(v)

% replace the diagonal elements of A with the elements of v
A = A + V

% display the updated matrix
disp(A)
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In this code snippet, we first create a 3x3 matrix A. Then, we create a vector v with 3 elements. To change the diagonal of A with v, we first diagonalize v using the diag function, which gives us a 3x3 matrix V with v on its diagonal. Then, we simply add V to A, which replaces the diagonal elements of A with the elements of v. Finally, we display the updated matrix using disp.