Hadamard's lemma explained

In mathematics, Hadamard's lemma, named after Jacques Hadamard, is essentially a first-order form of Taylor's theorem, in which we can express a smooth, real-valued function exactly in a convenient manner.

Statement

Proof

References

• Book: Nestruev, Jet. Smooth manifolds and observables. Springer. Berlin. 2002. 0-387-95543-7.