How can I add a 0db noise to my randomly generated data?

I simulated some random data and wish to add different db levels of noise to the data below

n = 5000;
m = 5000;
r =5;

Wtheo = 10*rand(m,r);
Htheo = 10*rand(r,n);
X = Wtheo*Htheo; % Synthetic Data

N = 7.5*randn(m,n);
SNR = snr(X,N); % this gives me an SNR of 25db.
%  How do I get 0 db? Is there a better way to do this?
data = X + N;

Answer 1

[Hiro Yoshino]

why don't you use awgn?

https://jp.mathworks.com/help/comm/ref/awgn.html

you can basically add whatever you want.