Which of these do you want to learn more about: - What e^A means when A is a matrix - How to think about solutions to linear systems of ordinary differential equations.
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As in, this is the sort of fact you could know should be true before seeing it, if you're comfortable enough with what it means to exponentiate a matrix, and Hermitian matrices.
To be honest, I still think it's shocking! I like the result because it's the kind of thing that might ultimately be used to prove things about quantum computational complexity (and maybe, classical computational complexity).
