Hi everyone. There is a constraint as below:

This constraint only has two variables: Sk,j[n] and qj[n].

Obviously, the first part Rk.m[N] is a quadratic term repect to qj[n]. And the constant Ak,j[n] >= 0. Thus, the first part Rk.m[N] is concave. The second part which has the -log function is certainly concave. In conclusion, this constraint is convex.

But when I use cvx, it always says: Illegal operation: log( {convex} ). I understand that in cvx, we should make sure the formula within the log function should be concave. But I have no idea how to write the above convex constraint legally.

Thanks in advance!