grandes-ecoles 2016 QII.A.1

grandes-ecoles · France · centrale-maths1__psi Matrices Matrix Norm, Convergence, and Inequality
For all $(M, N) \in (\mathcal{M}_n(\mathbb{R}))^2$, we denote $$(M \mid N) = \operatorname{tr}({}^t M N)$$ Prove that this defines an inner product on $\mathcal{M}_n(\mathbb{R})$. Explicitly express $(M \mid N)$ in terms of the coefficients of $M$ and $N$.
For all $(M, N) \in (\mathcal{M}_n(\mathbb{R}))^2$, we denote
$$(M \mid N) = \operatorname{tr}({}^t M N)$$
Prove that this defines an inner product on $\mathcal{M}_n(\mathbb{R})$. Explicitly express $(M \mid N)$ in terms of the coefficients of $M$ and $N$.