I’m trying to solve the following problem:

cvx_begin

variable f nonnegative

minimize 256e4.*inv_pos(f) + 1.28e-29.*pow_p(f, 3)

subject to

0 <= f;

f <= 2.8e9;

cvx_end

It has a closed form solution with value around 5e8. I tried all different solvers and still get a wrong solutions around 1e4.

This obective function is a part of my original one, so I need to get this part right. Thanks.