hi , when i write this expression in cvx for difference convex algorithm, i take this error. but when i run this term seperatly i take real answer but in cvx itteration not.
all matrixes are semidefinite matrix
QVhat = initial point for DC
QV is variable
Hsr are channle gain

If you know the expression would be real if computed without roundoff error, then use real as I showed (that will get rid of the imaginary part which CVX objects to, even if it is of tiny magnitude). if that is not the case, and you don’t want the real part, then you have a bad problem formulation.

Can I understand your words is this way:CVX can not solve the problem in {convex} + {complex affine} form,and the only way to fix it is to reformulate the problem ？

it is not possible to determine the convexity (curvature) of that. If part of an expression is not affine, the entire expression must evaluate to real in order for CVX to have any possibility of dealing with it.

Your first step is to prove that your optimization problem is convex.