How do I solve this problem?

This is what's on my mind:

n=-10:10; 
x= .....; 
E=sum(abs(x).^2); 
Pav=E/length(x);

I don't know how to represent x which should be the function itself and I don't know how to transform it to a loop.

[Walter Roberson]

Does u stand for the unit step function, better known as the Heaviside function?

[Mohamed El-Behairy]

@Walter yes it does

[Joseph Cheng]

start off small and define u[n] first as a function or condition. let me suggest looking up anonymous functions.

Answer 1

[Walter Roberson]

function r = u(s)
  if s <= 0
    r = 0;
  else
    r = 1;
  end
end

Now you can call u(n) and u(n-k) in your loop in calculate x(n)

[Mohamed El-Behairy]

I don't understand what did you do @Walter?

[Joseph Cheng]

as you confirmed u[n] is the Heaviside function which is 1 when n>0 and 0 for n<=0. Walter created a function which checks the input 's' to see if it is less than 0 which then outputs 0, otherwise the output is 1. (or when s>0)

 But i thought the heaviside was 1 at 0  such that n>=0 was 1.

[Walter Roberson]

There is no definition of the value of Heaviside(0) . 0, 1, and 1/2 are all common. See HeavisideAtOrigin in Symbolic Toolbox Heaviside.

It's a simple enough edit to change the definition.

K = 4;
for J = [2 3 4 5 6 7]
  uJ = u(J);
  uJK = u(J-K);
  disp(uJ - uJK);
end