Why is my custom Conjugate gradient solver and MATLAB pcg() do not have the same result?

Hello

Based on some literature I tried to implement a C code based on this Matlab code for conjugate gradient solver. However, When I tried to compare the code published on Wikipedia with MATLAB pcg() function as follows:

rng default
A = sprand(400,400,.5);
A = A'*A;
b = sum(A,2);

x1 = pcg(A, b, 1e-4, 150);
x2 = conj_grad(A, b, 1e-4, 150);

cmp = abs(x1-x2) < 1e6*eps(min(abs(x1),abs(x2))); % to compare

function x_i = conj_grad(m_A, v_b, tol, iter)
    x_i = v_b;
    r = v_b - m_A * x_i;
    p = r;
    rsold = r' * r;

    for i = 1:iter
        Ap = m_A * p;
        alpha = rsold / (p' * Ap);
        x_i = x_i + alpha * p;
        r = r - alpha * Ap;
        rsnew = r' * r;
        if sqrt(rsnew) < tol
            fprintf('cg converged at iteration %d to a solution with relative residual %f', i, sqrt(rsnew));
            break;
        end
        p = r + (rsnew / rsold) * p;
        rsold = rsnew;
    end
end

I discovered that the custom made function does not converge as pcg() and the results are different for example:

     pcg()                        conj_grad()
---------------------------------------------    
    0.9906                         0.9959
    1.0118                         1.0056
    0.9989                         0.9999
    1.0201                         0.9970
    1.0049                         1.0139
    ......
        

Could someone give some hints please?

Thank you