Is x/log(1+x) concave? If yes? How can I use cvx solve the constraints " x/log(1+x) >= C", where C is constant.

Presuming `x >= 0`

, that would be `x >= log(1+x)*C`

, which is a non-convex constraint if C > 0, and is a convex constraint if C < 0.

You should be coming to us with a convex constraint, which you have proven to be convex, not asking us whether it is convex.

Yes, when x>0, it’s cocave. Expressing it is equivalent to Expressing the following

Received with thanks.

WoW! That is a great idea. Thank you~