Ask for a help about the cvx's error

(Ky L) #1

I want to use the code to solve the object function through cvx,but there is an error in cvx:
“Cannot perform the operation:{real affine}.*{concave}”. How can I change the expression about code?
please help me! thanks very much!

(Mark L. Stone) #2

x*log(1+y) is indefinite in x and y, i.e., neither convex nor concave, so can not b e used in CVX.

(Ky L) #3

The paper where I found the model says it is convex, so I don’t know how to continue ;
but about perspective function:t*log(x/t) is concave in domain of definition

(Ky L) #4

could you give me some suggestions to solve the problem? thank you very much!

(Mark L. Stone) #5

If the expression you wish to maximize is concave, prove it to us. Please read the link in my above post.

(Michal Adamaszek) #6

You are right that the perspective function is concave. But unless t_1 and t_2 are somehow related to t_0 you have no way to exploit that. Do you have such a relation somewhere in your constraints?