Cvx_pow raises an error

How do I type in powers in cvx?
I tried using cvx
_pow(u, 2) but it raises an error

There is no function or command cvx_pow .

List of functions which might be relevant, depending on what you’re trying to so.

For the most detailed documentation use

help cvx/power
help pow_abs
help pow_pos
help square_pos
help pow_pos 

You can also read a less detailed description in and

Perhaps you have not read the CVX Users’ Guide I recommend you do so in its entirety.