How to formulate this expression in CVX?

Hello,
could anyone suggest me how can I formulate below expression in CVX?

\sum_{i=1}^{u}\sum_{j=1}^{B}x_{ij}log(\sum_{k=1}^{u}x_{kj})

Thanks.

I believe -sum(entr(sum(x))) would do it. This follows since the double sum can be rewritten

where y_j=\sum_{i=1}^ux_{ij}, and entr$(y_j)=-y_j\log y_j$.