How can I extract the numbers divisible by 3 from the diagonal of a nxn matrix composed of random integers?

I can create a random matrix of nxn with integers in [100;1000] interval, for example:

n=input('Choose the number of lines and columns of the square matrix: ')

A=randi([100,1000], n, n)

D=diag(A)

So the numbers in D are the numbers from the main diagonal of A. Now I would like to extract the numbers in D that are divisible by 3 and create matrix with those numbers, how can i do this?

Answer 1

[KALYAN ACHARJYA]

n=input('Choose the number of lines and columns of the square matrix: ')
A=randi([100,1000], n, n)
D=diag(A)
mat=D(mod(D,3)==0)

[João]

Thank you, that works perfectly!