diff --git a/CHANGELOG_UNRELEASED.md b/CHANGELOG_UNRELEASED.md index 0a799011a8..4dd7666702 100644 --- a/CHANGELOG_UNRELEASED.md +++ b/CHANGELOG_UNRELEASED.md @@ -49,6 +49,8 @@ - in `measurable_realfun.v`: + lemmas `emeasurable_fun_itv_obnd_cbndP`, `emeasurable_fun_itv_bndo_bndcP`, `emeasurable_fun_itv_cc` +- in `derive.v`: + + lemmas `derivable_mxP`, `derive_mx` ### Changed - in `set_interval.v` diff --git a/theories/derive.v b/theories/derive.v index 18a80fa3df..2822109ff9 100644 --- a/theories/derive.v +++ b/theories/derive.v @@ -2125,3 +2125,72 @@ exact/derivable1_diffP/derivable_horner. Qed. End derive_horner. + +Section pointwise_derivable. +Context {R : realFieldType} {V W : normedModType R} {m n : nat}. +Implicit Types M : V -> 'M[R]_(m, n). + +Lemma derivable_mxP M t v : + derivable M t v <-> forall i j, derivable (fun x => M x i j) t v. +Proof. +split=> [|Mvt]. +- move=> /cvg_ex[/= l Mvtl] i j; apply/cvg_ex; exists (l i j). + apply/cvgrPdist_le => /= e e0. + move/cvgrPdist_le : Mvtl => /(_ _ e0)[/= r r0] rMvte. + near=> x. + apply: le_trans (rMvte x _ _). + + rewrite [leRHS]/Num.Def.normr/= mx_normrE. + apply: le_trans; last exact: le_bigmax. + by rewrite !mxE. + + rewrite /ball_/= sub0r normrN. + by near: x; exact: dnbhs0_lt. + + near: x; exact: nbhs_dnbhs_neq. +- apply/cvg_ex => /=. + exists (\matrix_(i < m, j < n) sval (cid ((cvg_ex _).1 (Mvt i j)))). + apply/cvgrPdist_le => /= e e0. + near=> x. + rewrite /Num.Def.normr/= mx_normrE (bigmax_le _ (ltW e0))//= => i _. + rewrite !mxE/=. + move: i; near: x; apply: filter_forall => /= i. + exact: ((cvgrPdist_le _ _).1 (svalP (cid ((cvg_ex _).1 (Mvt i.1 i.2))))). +Unshelve. all: by end_near. Qed. + +End pointwise_derivable. + +Section pointwise_derive. +Local Open Scope classical_set_scope. +Context {R : realFieldType} {V W : normedModType R} . + +Lemma derive_mx {m n : nat} (M : V -> 'M[R]_(m, n)) t v : + derivable M t v -> + 'D_v M t = \matrix_(i < m, j < n) 'D_v (fun t => M t i j) t. +Proof. +move=> /cvg_ex[/= l Mvtl]; apply/cvg_lim => //=; apply/cvgrPdist_le => /= e e0. +move/cvgrPdist_le : (Mvtl) => /(_ (e / 2)) /[!divr_gt0]// /(_ isT)[d /= d0 dle]. +near=> x. +rewrite [leLHS]/Num.Def.normr/= mx_normrE (bigmax_le _ (ltW e0))//= => -[i j] _. +rewrite [in leLHS]mxE/= [X in _ + X]mxE -(subrKA (l i j)). +rewrite (le_trans (ler_normD _ _))// (splitr e) lerD//. +- rewrite mxE. + suff : (h^-1 *: (M (h *: v + t) i j - M t i j)) @[h --> 0^'] --> l i j. + move/cvg_lim => /=; rewrite /derive /= => ->//. + by rewrite subrr normr0 divr_ge0// ltW. + apply/cvgrPdist_le => /= r r0. + move/cvgrPdist_le : Mvtl => /(_ r r0)[/= s s0] sr. + near=> y. + apply: (@le_trans _ _ (`|l - y^-1 *: (M (y *: v + t) - M t)|)). + rewrite [in leRHS]/Num.Def.normr/= mx_normrE. + by under eq_bigr do rewrite !mxE; exact: (le_bigmax _ _ (i, j)). + rewrite sr//=; last by near: y; exact: nbhs_dnbhs_neq. + by rewrite sub0r normrN; near: y; exact: dnbhs0_lt. +- rewrite mxE. + apply: (@le_trans _ _ `|l - x^-1 *: (M (x *: v + t) - M t)|). + rewrite [in leRHS]/Num.Def.normr/= mx_normrE/=. + under eq_bigr do rewrite !mxE. + apply: le_trans; last exact: le_bigmax. + by rewrite !mxE. + apply: dle => //=; last by near: x; exact: nbhs_dnbhs_neq. + by rewrite sub0r normrN; near: x; exact: dnbhs0_lt. +Unshelve. all: by end_near. Qed. + +End pointwise_derive.