water filling_cvx

I have this code in my matlab but it has an error as:

Incorrect number or types of inputs or outputs for function vec.

I would really appreciate it if you could help me to solve it.

I should emphasize that I installed cvx on my matla.

Np = 4;
Nsc= 4;
mu_l_n = [1.56247628361161e-06;
    1.59519914659906e-06;
    1.27498226759933e-06;
    1.03143933197703e-05];
tilde_P1_tot = 1000;
sigma2_dBm = -104;
sigma2 = 10^(sigma2_dBm / 10 - 3);
cvx_begin quiet

Unrecognized function or variable 'cvx_begin'.

    variable p1_l_n(Np)  % Power allocation vector, column vector
    term = (mu_l_n.^2 .* p1_l_n) / sigma2;  % Define term for clarity
    maximize(sum(log(1 + term)))  % Objective function to maximize sum rates
    subject to
        sum(p1_l_n) == tilde_P1_tot / Nsc;  % Total power constraint across subcarriers
        p1_l_n >= 0;  % Power must be non-negative
 cvx_end
 % Display the optimal power allocation
disp('Optimal power allocation:');
disp(p1_l_n);

Answer 1

[M.]

The code you provided works fine on my computer and outputs :

Optimal power allocation:
   62.4982
   62.4989
   62.4901
   62.5129

You have to make sure that the directory that stores the cvx toolbox is on your Matlab path.

[Nasrin]

@M.would you please share your code with me?

because it does not work for my friend and me.

[M.]

I simply launched your code with cvx installed...

[Nasrin]

@M.you might use a different version of Matlab. it does not work with matlab 2024.

thank you by the way.

[Walter Roberson]

@Nasrin

Is the problem with R2024a or R2024b ?

[Nasrin]

@Walter Roberson matlab R2024a