# Question from Boyd's Optimization Book

1. Dec 5, 2012

### newphysist

Hi,

I am reading Convex Optimization from Stephen Boyd's book on my own and I am stuck at math he mentions on Pg. 157 of his book which can be found here.

How does he write the following:

sup{uTP$^{T}_{i}$x | ||u||2 ≤ 1} = ||P$^{T}_{i}$x||2

Thanks guys

2. Dec 5, 2012