What actually this code explains? where it is used and how to interpret it?

y=norm(x,2)^2/numel(x)

x is compelex vector.

[Nicolas B.]

Could you please explain what is your question?

Answer 1

[Yuan Li]

In the signal processing field, y is the power of signal x.

the square of 2-norm of x can be seen as energy of x, numel(x) is the length of x, then the ratio of energy and signal length is the signal power.