Why are the same parameters in the same formula different from those outside cvx

1

My code is as follows. I can ensure that my parameters are absolutely correct
global B
global J
global N
global N_0
global D_k
global sum_gr
global h_k_u
global h_u_b
global h_j_m_max
global h_j_e
global b_jn
p_j1 = ones(J,N);

    cvx_begin

     variable   p_j(J,N) ;
     expression An1(J,N) ;
     expression An4(J,N) ;
     expression Bn2(J,N) ;
     expression obj(J,N) ;
     expression obj1 ;
     expression w(J,N) ;
     

            for j = 1:J
                for n =1:N
                    An1(j,n) =  b_jn(j,n).*B.*( log( 1+(h_j_m_max(j,n).*p_j(j,n)./(B.*N_0.*b_jn(j,n))) )/log(2) );
                    An4(j,n) = (abs(h_j_e(j,n))^2)./(sum_gr(1,1,n)+B.*N_0.*b_jn(j,n));
                    Bn2(j,n) = b_jn(j,n).*B.*( An4(j,n).*p_j(j,n)./( (1+An4(j,n).*p_j1(j,n)).*log(2) ) + log(1+An4(j,n).*p_j1(j,n))/log(2) - An4(j,n).*p_j1(j,n)./((1+An4(j,n).*p_j1(j,n)).*log(2)) );
                    obj(j,n) = 1e-6.*(0.4.*p_j(j,n));
                    obj1 = sum(sum(obj,2),1);
                    w(j,n) = An1(j,n)-Bn2(j,n);
                end
            end

            minimize(obj1)

            subject to
            p_j<1;
            p_j>0.3;

    cvx_end

The independent variable pj is solved as 0.3, and the parameter An1 is solved as a fully sparse matrix (abnormal) in cvx, while the same parameter An1 is normal outside cvx，can you tell me why？

2

That’s just the way it is. if you really need An1 to be full, you can set An1 = full(An1); after cvx_end.

Actually,because An1 is a CVX expression and not a CVX variable, if you want to be assured of having the “optimal” value of An1, you have to recompute it after cvx_end, starting from CVX variable values. I.e., after cvx_end, place the code:

    An1 = zeros(J,N);
    for j = 1:J
        for n =1:N
            An1(j,n) =  b_jn(j,n).*B.*( log( 1+(h_j_m_max(j,n).*p_j(j,n)./(B.*N_0.*b_jn(j,n))) )/log(2) );
        end
    end

In this situation, An1 follows the standard MATLAB double precision variable rules.