How to express (x^2+y^2+z^2)^a (x,y,z are optimization variables and a<1) in CVX? Thanks!

Thanks for your reply

This is neither convex nor concave when a < 0.5. When a = 0.5, it is the 2-norm.

As for 0.5 < a < 1 ?

How to express (x^2+y^2+z^2)^a (x,y,z are optimization variables and a<1) in CVX? Thanks!

Thanks for your reply

This is neither convex nor concave when a < 0.5. When a = 0.5, it is the 2-norm.

As for 0.5 < a < 1 ?