-- Mathlib/Analysis/Complex/Hadamard.lean
theorem norm_mul_invInterpStrip_le_one_of_mem_verticalClosedStrip (f : ℂ → E) (ε : ℝ) (hε : 0 < ε)
    (z : ℂ) (hd : DiffContOnCl ℂ f (verticalStrip 0 1))
    (hB : BddAbove ((norm ∘ f) '' verticalClosedStrip 0 1)) (hz : z ∈ verticalClosedStrip 0 1) :
    ‖F f ε z‖ ≤ 1

Proof state:
case h
E : Type u_1
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace ℂ E
f : ℂ → E
ε : ℝ
hε : 0 < ε
z : ℂ
hd : DiffContOnCl ℂ f (verticalStrip 0 1)
hB : BddAbove (norm ∘ f '' verticalClosedStrip 0 1)
hz : z ∈ verticalClosedStrip 0 1
BF : ℝ
hBF : ∀ a ∈ verticalClosedStrip 0 1, ‖F f ε a‖ ≤ BF
⊢ (fun x => invInterpStrip f x ε • f x) =O[comap (abs ∘ im) atTop ⊓ 𝓟 (re ⁻¹' Ioo 0 1)] fun z =>
    Real.exp (BF * Real.exp (0 * |z.im|))

Tactic:
rw [Asymptotics.isBigO_iff]

Result:
case h
E : Type u_1
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace ℂ E
f : ℂ → E
ε : ℝ
hε : 0 < ε
z : ℂ
hd : DiffContOnCl ℂ f (verticalStrip 0 1)
hB : BddAbove (norm ∘ f '' verticalClosedStrip 0 1)
hz : z ∈ verticalClosedStrip 0 1
BF : ℝ
hBF : ∀ a ∈ verticalClosedStrip 0 1, ‖F f ε a‖ ≤ BF
⊢ ∃ c,
    ∀ᶠ (x : ℂ) in comap (abs ∘ im) atTop ⊓ 𝓟 (re ⁻¹' Ioo 0 1),
      ‖invInterpStrip f x ε • f x‖ ≤ c * ‖Real.exp (BF * Real.exp (0 * |x.im|))‖

Proof state:
case h
E : Type u_1
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace ℂ E
f : ℂ → E
ε : ℝ
hε : 0 < ε
z : ℂ
hd : DiffContOnCl ℂ f (verticalStrip 0 1)
hB : BddAbove (norm ∘ f '' verticalClosedStrip 0 1)
hz : z ∈ verticalClosedStrip 0 1
BF : ℝ
hBF : ∀ a ∈ verticalClosedStrip 0 1, ‖F f ε a‖ ≤ BF
⊢ ∀ᶠ (x : ℂ) in comap (abs ∘ im) atTop ⊓ 𝓟 (re ⁻¹' Ioo 0 1),
    ‖invInterpStrip f x ε • f x‖ ≤ 1 * ‖Real.exp (BF * Real.exp (0 * |x.im|))‖

Tactic:
rw [eventually_inf_principal]

Result:
case h
E : Type u_1
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace ℂ E
f : ℂ → E
ε : ℝ
hε : 0 < ε
z : ℂ
hd : DiffContOnCl ℂ f (verticalStrip 0 1)
hB : BddAbove (norm ∘ f '' verticalClosedStrip 0 1)
hz : z ∈ verticalClosedStrip 0 1
BF : ℝ
hBF : ∀ a ∈ verticalClosedStrip 0 1, ‖F f ε a‖ ≤ BF
⊢ ∀ᶠ (x : ℂ) in comap (abs ∘ im) atTop,
    x ∈ re ⁻¹' Ioo 0 1 → ‖invInterpStrip f x ε • f x‖ ≤ 1 * ‖Real.exp (BF * Real.exp (0 * |x.im|))‖

Proof state:
case h.hp
E : Type u_1
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace ℂ E
f : ℂ → E
ε : ℝ
hε : 0 < ε
z : ℂ
hd : DiffContOnCl ℂ f (verticalStrip 0 1)
hB : BddAbove (norm ∘ f '' verticalClosedStrip 0 1)
hz : z ∈ verticalClosedStrip 0 1
BF : ℝ
hBF : ∀ a ∈ verticalClosedStrip 0 1, ‖F f ε a‖ ≤ BF
x : ℂ
hx : x ∈ re ⁻¹' Ioo 0 1
⊢ ‖invInterpStrip f x ε • f x‖ ≤ Real.exp BF

Tactic:
exact (hBF x ((preimage_mono Ioo_subset_Icc_self) hx)).trans
  ((le_of_lt (lt_add_one BF)).trans (Real.add_one_le_exp BF))

Result:
no goals

Proof state:
case h.hp
E : Type u_1
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace ℂ E
f : ℂ → E
ε : ℝ
hε : 0 < ε
z : ℂ
hd : DiffContOnCl ℂ f (verticalStrip 0 1)
hB : BddAbove (norm ∘ f '' verticalClosedStrip 0 1)
hz : z ∈ verticalClosedStrip 0 1
BF : ℝ
hBF : ∀ a ∈ verticalClosedStrip 0 1, ‖F f ε a‖ ≤ BF
⊢ ∀ x ∈ re ⁻¹' Ioo 0 1, ‖invInterpStrip f x ε • f x‖ ≤ 1 * ‖Real.exp (BF * Real.exp (0 * |x.im|))‖

Tactic:
intro x hx

Result:
case h.hp
E : Type u_1
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace ℂ E
f : ℂ → E
ε : ℝ
hε : 0 < ε
z : ℂ
hd : DiffContOnCl ℂ f (verticalStrip 0 1)
hB : BddAbove (norm ∘ f '' verticalClosedStrip 0 1)
hz : z ∈ verticalClosedStrip 0 1
BF : ℝ
hBF : ∀ a ∈ verticalClosedStrip 0 1, ‖F f ε a‖ ≤ BF
x : ℂ
hx : x ∈ re ⁻¹' Ioo 0 1
⊢ ‖invInterpStrip f x ε • f x‖ ≤ 1 * ‖Real.exp (BF * Real.exp (0 * |x.im|))‖

Proof state:
E : Type u_1
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace ℂ E
f : ℂ → E
ε : ℝ
hε : 0 < ε
z : ℂ
hd : DiffContOnCl ℂ f (verticalStrip 0 1)
hB : BddAbove (norm ∘ f '' verticalClosedStrip 0 1)
hz : z ∈ verticalClosedStrip 0 1
⊢ ∃ c < Real.pi / (1 - 0),
    ∃ B,
      (fun x => invInterpStrip f x ε • f x) =O[comap (abs ∘ im) atTop ⊓ 𝓟 (re ⁻¹' Ioo 0 1)] fun z =>
        Real.exp (B * Real.exp (c * |z.im|))

Tactic:
use 0

Result:
case h
E : Type u_1
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace ℂ E
f : ℂ → E
ε : ℝ
hε : 0 < ε
z : ℂ
hd : DiffContOnCl ℂ f (verticalStrip 0 1)
hB : BddAbove (norm ∘ f '' verticalClosedStrip 0 1)
hz : z ∈ verticalClosedStrip 0 1
⊢ 0 < Real.pi / (1 - 0) ∧
    ∃ B,
      (fun x => invInterpStrip f x ε • f x) =O[comap (abs ∘ im) atTop ⊓ 𝓟 (re ⁻¹' Ioo 0 1)] fun z =>
        Real.exp (B * Real.exp (0 * |z.im|))

Proof state:
case h
E : Type u_1
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace ℂ E
f : ℂ → E
ε : ℝ
hε : 0 < ε
z : ℂ
hd : DiffContOnCl ℂ f (verticalStrip 0 1)
hB : BddAbove (norm ∘ f '' verticalClosedStrip 0 1)
hz : z ∈ verticalClosedStrip 0 1
⊢ 0 < Real.pi / (1 - 0) ∧
    ∃ B,
      (fun x => invInterpStrip f x ε • f x) =O[comap (abs ∘ im) atTop ⊓ 𝓟 (re ⁻¹' Ioo 0 1)] fun z =>
        Real.exp (B * Real.exp (0 * |z.im|))

Tactic:
rw [sub_zero, div_one]

Result:
case h
E : Type u_1
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace ℂ E
f : ℂ → E
ε : ℝ
hε : 0 < ε
z : ℂ
hd : DiffContOnCl ℂ f (verticalStrip 0 1)
hB : BddAbove (norm ∘ f '' verticalClosedStrip 0 1)
hz : z ∈ verticalClosedStrip 0 1
⊢ 0 < Real.pi ∧
    ∃ B,
      (fun x => invInterpStrip f x ε • f x) =O[comap (abs ∘ im) atTop ⊓ 𝓟 (re ⁻¹' Ioo 0 1)] fun z =>
        Real.exp (B * Real.exp (0 * |z.im|))

Proof state:
case h
E : Type u_1
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace ℂ E
f : ℂ → E
ε : ℝ
hε : 0 < ε
z : ℂ
hd : DiffContOnCl ℂ f (verticalStrip 0 1)
hB : BddAbove (norm ∘ f '' verticalClosedStrip 0 1)
hz : z ∈ verticalClosedStrip 0 1
BF : ℝ
hBF : ∀ a ∈ verticalClosedStrip 0 1, ‖F f ε a‖ ≤ BF
⊢ ∃ c,
    ∀ᶠ (x : ℂ) in comap (abs ∘ im) atTop ⊓ 𝓟 (re ⁻¹' Ioo 0 1),
      ‖invInterpStrip f x ε • f x‖ ≤ c * ‖Real.exp (BF * Real.exp (0 * |x.im|))‖

Tactic:
use 1

Result:
case h
E : Type u_1
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace ℂ E
f : ℂ → E
ε : ℝ
hε : 0 < ε
z : ℂ
hd : DiffContOnCl ℂ f (verticalStrip 0 1)
hB : BddAbove (norm ∘ f '' verticalClosedStrip 0 1)
hz : z ∈ verticalClosedStrip 0 1
BF : ℝ
hBF : ∀ a ∈ verticalClosedStrip 0 1, ‖F f ε a‖ ≤ BF
⊢ ∀ᶠ (x : ℂ) in comap (abs ∘ im) atTop ⊓ 𝓟 (re ⁻¹' Ioo 0 1),
    ‖invInterpStrip f x ε • f x‖ ≤ 1 * ‖Real.exp (BF * Real.exp (0 * |x.im|))‖

Proof state:
case h
E : Type u_1
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace ℂ E
f : ℂ → E
ε : ℝ
hε : 0 < ε
z : ℂ
hd : DiffContOnCl ℂ f (verticalStrip 0 1)
hB : BddAbove (norm ∘ f '' verticalClosedStrip 0 1)
hz : z ∈ verticalClosedStrip 0 1
BF : ℝ
hBF : ∀ a ∈ verticalClosedStrip 0 1, ‖F f ε a‖ ≤ BF
⊢ ∀ᶠ (x : ℂ) in comap (abs ∘ im) atTop,
    x ∈ re ⁻¹' Ioo 0 1 → ‖invInterpStrip f x ε • f x‖ ≤ 1 * ‖Real.exp (BF * Real.exp (0 * |x.im|))‖

Tactic:
apply Eventually.of_forall

Result:
case h.hp
E : Type u_1
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace ℂ E
f : ℂ → E
ε : ℝ
hε : 0 < ε
z : ℂ
hd : DiffContOnCl ℂ f (verticalStrip 0 1)
hB : BddAbove (norm ∘ f '' verticalClosedStrip 0 1)
hz : z ∈ verticalClosedStrip 0 1
BF : ℝ
hBF : ∀ a ∈ verticalClosedStrip 0 1, ‖F f ε a‖ ≤ BF
⊢ ∀ x ∈ re ⁻¹' Ioo 0 1, ‖invInterpStrip f x ε • f x‖ ≤ 1 * ‖Real.exp (BF * Real.exp (0 * |x.im|))‖