mathlib3

5d9e7f58 - feat(analysis/calculus/fderiv): define `has_strict_fderiv_at` (#2249)

feat(analysis/calculus/fderiv): define `has_strict_fderiv_at` (#2249) * Move code aroud * general constructions (product, chain rule) before arithmetic; * bundled `E →L[𝕜] F` maps before unbundled * Use `maps_to` instead of `f '' _ ⊆ _` * feat(analysis/calculus/fderiv): define `has_strict_fderiv_at` Prove strict differentiability of all functions found in this file, cleanup. * Update src/analysis/calculus/fderiv.lean Co-Authored-By: sgouezel <sebastien.gouezel@univ-rennes1.fr> * Docs, var name Co-authored-by: sgouezel <sebastien.gouezel@univ-rennes1.fr> Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>