find a nonsingular matrix p such that p^{-1}ap is a diagonal matrix. in matlab

main.m
% Given matrix a
a = [1, 2; 3, 4];

% Compute eigenvalues and eigenvectors
[V, D] = eig(a);

% Create nonsingular matrix P using the eigenvectors
P = V;

% Calculate the inverse of P
P_inv = inv(P);

% Calculate the diagonal matrix using eigenvalues
D = diag(diag(D));

% Verify the result
result = P_inv * a * P;  % should be a diagonal matrix

disp(result);
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