English
The derivative of bernoulliFun with respect to x satisfies HasDerivAt(bernoulliFun k, k·bernoulliFun(k−1) x, x).
Русский
Производная bernoulliFun по x равна k·bernoulliFun(k−1)(x).
LaTeX
$$$$ \\text{HasDerivAt}(\\bernoulliFun(k), k \\cdot \\bernoulliFun(k-1)(x), x). $$$$
Lean4
theorem hasDerivAt_bernoulliFun (k : ℕ) (x : ℝ) : HasDerivAt (bernoulliFun k) (k * bernoulliFun (k - 1) x) x :=
by
convert ((Polynomial.bernoulli k).map <| algebraMap ℚ ℝ).hasDerivAt x using 1
simp only [bernoulliFun, Polynomial.derivative_map, Polynomial.derivative_bernoulli k, Polynomial.map_mul,
Polynomial.map_natCast, Polynomial.eval_mul, Polynomial.eval_natCast]