# Cannot perform the operation: {mixed real affine/complex affine} ./ {real affine}

``````cvx_begin
variable W(M,M,K) complex hermitian;
variable wk;
variables t(K) u(K);
variable beta0;
expressions xi lambda tau;

%-------C12-------------
xi=1;                         %ξPower amplifier efficiency
lambda>0;
tau>=lambda*Pc;
tau<=lambda*(Pmax+Pc);    %τ
%-------C1：W,1-K sum---------
Wkk=0;
for kk=1:K
Wkk=Wkk+W(:,:,kk);
end
%------W：k+1-K sum-------
Wi=0;
i=1;
for k=1:K
if i<=K
Wi=Wi+W(:,:,i);
end
Wk=W(:,:,k);
end
dk1=sqrt((deltaH^2)*chi2inv(0.5,2*M*N))*(1/2);   %1*1
dk2=sqrt((deltaH^2)*chi2inv(0.5,2*M*N))^(1/2);
Qk1=kron((Wk/gamma_tar-Wi)',THETA0);      %(M*N+M)*(M*N+M)
Qk2=kron((Wk/beta0-Wi)',THETA0);
``````

up there is part of my code, every time I run this would be stuck at Qk2 and display this:Disciplined convex programming error:
** Cannot perform the operation: {mixed real**
** affine/complex affine} ./ {real affine}**
but Qk1 is fine, I don’t know how to deal with it.

I don’t know why `Qk1` is not also producing an error message. Apparently, because of `

``````disp((Wk/gamma_tar-Wi)')
cvx zero expression (scalar)
``````

But I don’t understand why that is happening.

Anyhow, have you proven your optimization problem is convex?

Thanks for your patient reply. After I asked this question I checked my code, and found that I defined beta0 in Qk2 as a variable. Actually, it not really a optimization variable but a variable that need iteration method to find out. And I solved it.