How to express (1/x)*log(1+1/y)

截屏2022-07-26 下午3.06.33

Neither convex nor concave.

Thank you, Mark. When x>0,y>0, (1/x)*log(1+1/y) is convex. Thus, how do I express this equation in CVX when both x and y are positive numbers?

You don’t. It’s not convex over the entirety of its natural domain.