I want to know how to compute the proximal mapping of this function:
$f(x) = \sup_y(yx - \frac{1}{2}\sigma y^2 ), \|y\|_{\infty} < \beta$
I know how to compute the proximal mapping when $\beta$ is 1, but I don't know how to do it when $\beta \neq 1$.
Do you guys have any ideas?