Module: Mathlib.Analysis.SpecialFunctions.Elliptic.Weierstrass

Goal state before:
pp: case neg
L : PeriodPair
l₀ z x : ℂ
hx : ∀ (l : ↥L.lattice), ↑l ≠ l₀ → ‖z - x‖ < ‖↑l - x‖
κ : ℝ
hκ : 1 < κ
hκ' : ∀ (l : ↥L.lattice), ↑l ≠ l₀ → ‖z - x‖ * κ < ‖↑l - x‖
e : ℕ × ↥L.lattice ≃ ↥L.lattice ⊕ ℕ × ↥L.lattice :=
  (Equiv.prodCongrLeft fun x ↦ (Denumerable.eqv (Option ℕ)).symm).trans optionProdEquiv
H₁ : Summable fun i ↦ (↑i + 2) * κ ^ (-↑i)
H₂ : Summable fun l ↦ ‖↑l - x‖ ^ (-3) * ‖z - x‖
p : ℕ × ↥L.lattice
hp :
  ¬↑((Equiv.prodCongrLeft fun x ↦
              { toFun := Encodable.encode, invFun := Denumerable.ofNat (Option ℕ), left_inv := ⋯, right_inv := ⋯ })
            (Prod.map some id p)).2 =
      l₀
hpx : ‖↑p.2 - x‖ ≠ 0
⊢ ‖((↑((Equiv.prodCongrLeft fun x ↦
                      { toFun := Encodable.encode, invFun := Denumerable.ofNat (Option ℕ), left_inv := ⋯,
                        right_inv := ⋯ })
                    (Prod.map some id p)).1 +
              1) *
            (↑((Equiv.prodCongrLeft fun x ↦
                        { toFun := Encodable.encode, invFun := Denumerable.ofNat (Option ℕ), left_inv := ⋯,
                          right_inv := ⋯ })
                      (Prod.map some id p)).2 -
                x) ^
              (-(↑((Equiv.prodCongrLeft fun x ↦
                          { toFun := Encodable.encode, invFun := Denumerable.ofNat (Option ℕ), left_inv := ⋯,
                            right_inv := ⋯ })
                        (Prod.map some id p)).1 +
                  2)) -
          Nat.rec
            (↑((Equiv.prodCongrLeft fun x ↦
                      { toFun := Encodable.encode, invFun := Denumerable.ofNat (Option ℕ), left_inv := ⋯,
                        right_inv := ⋯ })
                    (Prod.map some id p)).2 ^
              (-2))
            (fun n n_ih ↦ 0)
            ((Equiv.prodCongrLeft fun x ↦
                  { toFun := Encodable.encode, invFun := Denumerable.ofNat (Option ℕ), left_inv := ⋯, right_inv := ⋯ })
                (Prod.map some id p)).1) *
        (z - x) ^
          ((Equiv.prodCongrLeft fun x ↦
                { toFun := Encodable.encode, invFun := Denumerable.ofNat (Option ℕ), left_inv := ⋯, right_inv := ⋯ })
              (Prod.map some id p)).1‖ ≤
    (↑p.1 + 2) * κ ^ (-↑p.1) * (‖↑p.2 - x‖ ^ (-3) * ‖z - x‖)

Tactic:
obtain rfl | hxz := eq_or_ne z x

Goal state after:
case neg.inl
L : PeriodPair
l₀ z : ℂ
κ : ℝ
hκ : 1 < κ
e : ℕ × ↥L.lattice ≃ ↥L.lattice ⊕ ℕ × ↥L.lattice :=
  (Equiv.prodCongrLeft fun x ↦ (Denumerable.eqv (Option ℕ)).symm).trans optionProdEquiv
H₁ : Summable fun i ↦ (↑i + 2) * κ ^ (-↑i)
p : ℕ × ↥L.lattice
hp :
  ¬↑((Equiv.prodCongrLeft fun x ↦
              { toFun := Encodable.encode, invFun := Denumerable.ofNat (Option ℕ), left_inv := ⋯, right_inv := ⋯ })
            (Prod.map some id p)).2 =
      l₀
hx : ∀ (l : ↥L.lattice), ↑l ≠ l₀ → ‖z - z‖ < ‖↑l - z‖
hκ' : ∀ (l : ↥L.lattice), ↑l ≠ l₀ → ‖z - z‖ * κ < ‖↑l - z‖
H₂ : Summable fun l ↦ ‖↑l - z‖ ^ (-3) * ‖z - z‖
hpx : ‖↑p.2 - z‖ ≠ 0
⊢ ‖((↑((Equiv.prodCongrLeft fun x ↦
                      { toFun := Encodable.encode, invFun := Denumerable.ofNat (Option ℕ), left_inv := ⋯,
                        right_inv := ⋯ })
                    (Prod.map some id p)).1 +
              1) *
            (↑((Equiv.prodCongrLeft fun x ↦
                        { toFun := Encodable.encode, invFun := Denumerable.ofNat (Option ℕ), left_inv := ⋯,
                          right_inv := ⋯ })
                      (Prod.map some id p)).2 -
                z) ^
              (-(↑((Equiv.prodCongrLeft fun x ↦
                          { toFun := Encodable.encode, invFun := Denumerable.ofNat (Option ℕ), left_inv := ⋯,
                            right_inv := ⋯ })
                        (Prod.map some id p)).1 +
                  2)) -
          Nat.rec
            (↑((Equiv.prodCongrLeft fun x ↦
                      { toFun := Encodable.encode, invFun := Denumerable.ofNat (Option ℕ), left_inv := ⋯,
                        right_inv := ⋯ })
                    (Prod.map some id p)).2 ^
              (-2))
            (fun n n_ih ↦ 0)
            ((Equiv.prodCongrLeft fun x ↦
                  { toFun := Encodable.encode, invFun := Denumerable.ofNat (Option ℕ), left_inv := ⋯, right_inv := ⋯ })
                (Prod.map some id p)).1) *
        (z - z) ^
          ((Equiv.prodCongrLeft fun x ↦
                { toFun := Encodable.encode, invFun := Denumerable.ofNat (Option ℕ), left_inv := ⋯, right_inv := ⋯ })
              (Prod.map some id p)).1‖ ≤
    (↑p.1 + 2) * κ ^ (-↑p.1) * (‖↑p.2 - z‖ ^ (-3) * ‖z - z‖)

case neg.inr
L : PeriodPair
l₀ z x : ℂ
hx : ∀ (l : ↥L.lattice), ↑l ≠ l₀ → ‖z - x‖ < ‖↑l - x‖
κ : ℝ
hκ : 1 < κ
hκ' : ∀ (l : ↥L.lattice), ↑l ≠ l₀ → ‖z - x‖ * κ < ‖↑l - x‖
e : ℕ × ↥L.lattice ≃ ↥L.lattice ⊕ ℕ × ↥L.lattice :=
  (Equiv.prodCongrLeft fun x ↦ (Denumerable.eqv (Option ℕ)).symm).trans optionProdEquiv
H₁ : Summable fun i ↦ (↑i + 2) * κ ^ (-↑i)
H₂ : Summable fun l ↦ ‖↑l - x‖ ^ (-3) * ‖z - x‖
p : ℕ × ↥L.lattice
hp :
  ¬↑((Equiv.prodCongrLeft fun x ↦
              { toFun := Encodable.encode, invFun := Denumerable.ofNat (Option ℕ), left_inv := ⋯, right_inv := ⋯ })
            (Prod.map some id p)).2 =
      l₀
hpx : ‖↑p.2 - x‖ ≠ 0
hxz : z ≠ x
⊢ ‖((↑((Equiv.prodCongrLeft fun x ↦
                      { toFun := Encodable.encode, invFun := Denumerable.ofNat (Option ℕ), left_inv := ⋯,
                        right_inv := ⋯ })
                    (Prod.map some id p)).1 +
              1) *
            (↑((Equiv.prodCongrLeft fun x ↦
                        { toFun := Encodable.encode, invFun := Denumerable.ofNat (Option ℕ), left_inv := ⋯,
                          right_inv := ⋯ })
                      (Prod.map some id p)).2 -
                x) ^
              (-(↑((Equiv.prodCongrLeft fun x ↦
                          { toFun := Encodable.encode, invFun := Denumerable.ofNat (Option ℕ), left_inv := ⋯,
                            right_inv := ⋯ })
                        (Prod.map some id p)).1 +
                  2)) -
          Nat.rec
            (↑((Equiv.prodCongrLeft fun x ↦
                      { toFun := Encodable.encode, invFun := Denumerable.ofNat (Option ℕ), left_inv := ⋯,
                        right_inv := ⋯ })
                    (Prod.map some id p)).2 ^
              (-2))
            (fun n n_ih ↦ 0)
            ((Equiv.prodCongrLeft fun x ↦
                  { toFun := Encodable.encode, invFun := Denumerable.ofNat (Option ℕ), left_inv := ⋯, right_inv := ⋯ })
                (Prod.map some id p)).1) *
        (z - x) ^
          ((Equiv.prodCongrLeft fun x ↦
                { toFun := Encodable.encode, invFun := Denumerable.ofNat (Option ℕ), left_inv := ⋯, right_inv := ⋯ })
              (Prod.map some id p)).1‖ ≤
    (↑p.1 + 2) * κ ^ (-↑p.1) * (‖↑p.2 - x‖ ^ (-3) * ‖z - x‖)