I got a problem about the expression about" log（sum（inv_pos(x+a)）+b）".

cvx_begin

variable x(n,1)

maximize(-log(sum（inv_pos(x+a)）+b))

subject to

…

cvx_end

An error occur:

Illegal operation: log( {convex} ).

Can anyone help me to give an idea for feasible expression by using CVX.

Thanks alot.