Possible Duplicate:
Square root of a matrix
Prove that if all eigenvalues of a matrix $A \in \mathcal{M} (n,n; \mathbb{R} )$ are real, then there exists $B \in \mathcal{M} (n,n; \mathbb{R} ) $ such that $B^2=A$.
Could you help me solve it?
Possible Duplicate:
Square root of a matrix
Prove that if all eigenvalues of a matrix $A \in \mathcal{M} (n,n; \mathbb{R} )$ are real, then there exists $B \in \mathcal{M} (n,n; \mathbb{R} ) $ such that $B^2=A$.
Could you help me solve it?