Hello. I am relatively new in cvx.

I have the function: f(x,y)=1/(x^2+y^2 ).

I compute the Hessian and I believe it is a convex function on (x,y).

If it is convex (cross-finger). Then, I would like to write its perspective function in the cvx format:

t/((x/t)^2+(y/t)^2 ).

So, my question is, assuming that f(x,y)=1/(x^2+y^2 ) is convex. How can I write its perspective function using the cvx rules?

# How to write a Perspective function in cvx? (Moderator note: this is non-convex because underlying function in this post is non-convex)

**lrcantos**(Luiggi) #1

**Mark_L_Stone**(Mark L. Stone) #3

`1/(x^2 + y^2)`

is not convex. Its Hessian has one negative eigenvalue and one positive eigenvalue for all values of `x`

and `y`

.