English
If f is strictly differentiable at p and f₂ is strictly differentiable at p, then Prod.map f f₂ is strictly differentiable with derivative f' ∘ f₂'.
Русский
Если f и f₂ строго дифференцируемы в p, то Prod.map f f₂ строго дифференцируем и его производная равна f'∘f₂'.
LaTeX
$$HasStrictFDerivAt.prodMap (hf) (hf₂) : HasStrictFDerivAt (Prod.map f f₂) (f'.prodMap f₂') p$$
Lean4
@[simp, fun_prop]
protected theorem snd (h : Differentiable 𝕜 f₂) : Differentiable 𝕜 fun x => (f₂ x).2 :=
differentiable_snd.comp h