grandes-ecoles 2023 Q3

grandes-ecoles · France · mines-ponts-maths2__pc Taylor series Prove smoothness or power series expandability of a function
Let $t \in \mathbf{R}$ and $(i,j) \in \llbracket 1;N \rrbracket^2$, justify that the series $\sum_{n \geq 0} \frac{t^n K^n[i,j]}{n!}$ converges. We denote by $H_t \in \mathscr{M}_N(\mathbf{R})$ the matrix defined by $$\forall (i,j) \in \llbracket 1;N \rrbracket^2, H_t[i,j] = e^{-t} \sum_{n=0}^{+\infty} \frac{t^n K^n[i,j]}{n!}$$
Let $t \in \mathbf{R}$ and $(i,j) \in \llbracket 1;N \rrbracket^2$, justify that the series $\sum_{n \geq 0} \frac{t^n K^n[i,j]}{n!}$ converges.\\
We denote by $H_t \in \mathscr{M}_N(\mathbf{R})$ the matrix defined by
$$\forall (i,j) \in \llbracket 1;N \rrbracket^2, H_t[i,j] = e^{-t} \sum_{n=0}^{+\infty} \frac{t^n K^n[i,j]}{n!}$$