Norm & Illegal operation: log( {convex} )

cvx_begin quiet
variable v_l(M,1) complex
for k=1:K
for i=i:K
h_ki=squeeze(h_rki(k,i,:))’;%默认是行
Q_A=Q_A+p(i)square_pos(norm(h_kiv_l+gdk(i),2));
end
y=y+TBlog(Q_A)/log(2);
end

error: y=y+TBlog(Q_A)/log(2);
isciplined convex programming error:
Illegal operation: log( {convex} ).
I think Q_A is convex,why is error ?

You cannot have nonlinear equalities if you want a convex problem.

Those are actually assignments, not equality constraints. So in effect just adding terms.

The error is due to log of norm squared, which is neither convex nor concave.

Thank you very much !!