set of positive definite matrices are the interior of set of positive semidefinite matrices

638 Views Asked by At

I'm studying a book and encountered with that: the set of positive definite matrices are the interior of set of positive semidefinite matrices.

What is the norm here?

1

There are 1 best solutions below

1
On

One can take the Frobenius norm $$ ||A||^2=\langle A,A\rangle=Tr(AA^T), $$ see the article Properties of positive (semi)definite matrices. Example $B5$ is the statement you have mentioned, on page $239$.