Help - Problem with fminsearch

Hi everyone,

I have three vectors that I calculated in MatLab with expression find previously.

Now I would create a function that maximize my utility function (U) and retourn me the values find analiticaly.

For this I writed this function:

function U = punto2(x, PC, p_a, p_m, p_s)

%Definiamo i parametri

omega_a = 0.33;
omega_m = 0.33;
omega_s = 0.33;

epsilon = 0.5;

cs_bar  = 0;                                                                                                
ca_bar  = 0; 
cm_bar  = 0;

% Dove x(1) = c_m and x(2)= c_s
   
 U = - (  ((omega_a^(1/epsilon))  * ( ((PC/p_a) - ((p_m*x(1))/p_a) - ((p_s*x(2))/p_a)) + ca_bar )^((epsilon-1)/epsilon)...
     + (omega_m^(1/epsilon)) * (x(1) + cm_bar)^((epsilon-1)/epsilon)...
     + (omega_s^(1/epsilon)) * (x(2) + cs_bar)^((epsilon-1)/epsilon) )^(epsilon/(epsilon-1))  );

Where U is the function that i would maximize.

Now, when I call the function in my main script in this way:

z0 = [0.333 0.333];

max_U(t,:) = fminsearch(@(x) punto2(x, PC, p_a, p_m, p_s), z0);

MatLab retourn me different values except for the first.

Info: The function is recalled inside the for loop.

Some help?