How do I take square roots of certain entries of a tridiagonal matrix?

So I have a 50 by 50 tridiagonal matrix. The entries along the main diagonal are 0 and the entries above and below are -square root (k(N-k) where N is 50 and k is an integer from 1 to 50. I am completely new to matlab and have no programming experience. Can someone please help?

Answer 1

[Guillaume]

N = 50;

v = 1:N-1; %a 50x50 matrix only have 49 elements above and below diagonal
m = full(gallery('tridiag', -sqrt(v.*(N-v)), zeros(1, N), -sqrt(v.*(N-v))))

[Z M]

Please forgive, but do I just type into matlab as is? The next part is to find eigenvalues, will this affect the code any?

[Guillaume]

Paste it in the command window, or a script, or a function, and try.

Also look up gallery documentation, particularly, the 'tridiag' option.

Once you've constructed your tridiagonal matrix, you can use it any way you see fit.

[Z M]

Thank you so much!