MHB Math Helper
- Jan 29, 2012
I quote a question from Yahoo! Answers
I have given a link to the topic there so the OP can see my response.1. Prove that if X ∈ R^(d×n) then XX^T and X^TX are both positive semidefinite.
6. Prove that if X ∈ R^(d×n) has rank d, then XX^T is positive definite (invertible).