Dear experts,

The constraints in my problem is “x^3-2<=18, x>=0”. Obviously, this imposes a convex set of the variable x. The problem is how to express this constraint in CVX? The error shows “Disciplined convex programming error: Illegal operation: {real affine} .^ {3} (Consider POW_P, POW_POS, or POW_ABS instead.)” in CVX. I need your help. If it is convenient for you, please help me. I am looking forward to your reply.

This has now been corrected.

`pow_p(x,3) <= 18`

or

`pow_pos(x,3) <= 18`

Did the error message not give you enough of a clue to get you to look up those functions?

Thanks for your reply. I cannot find a clue from the error message. Besides, when I use pow_p(x) <= 18 and pow_pos(x) <= 18 to replace x^3<=18, there still exists errors. The output message indicates input parameters are not enough when using cvx/pow_pos . Maybe it needs two input parameters, but I have no idea about the second input parameter. Could you please help me with this problem? Thanks for your time.

Sorry, I forgot to type the 2nd argument. I have corrected my post to include it.

I got it. Thank you very much.