-- Mathlib/NumberTheory/LSeries/MellinEqDirichlet.lean
/-- Tailored version for odd Jacobi theta functions. -/
lemma hasSum_mellin_pi_mul_sq' {a : ι → ℂ} {r : ι → ℝ} {F : ℝ → ℂ} {s : ℂ} (hs : 0 < s.re)
    (hF : ∀ t ∈ Ioi 0, HasSum (fun i ↦ a i * r i * rexp (-π * r i ^ 2 * t)) (F t))
    (h_sum : Summable fun i ↦ ‖a i‖ / |r i| ^ s.re) :
    HasSum (fun i ↦ Gammaℝ (s + 1) * a i * SignType.sign (r i) / |r i| ^ s)
    (mellin F ((s + 1) / 2))

Proof state:
case h.e'_5.h.inr
ι : Type u_1
inst✝ : Countable ι
a : ι → ℂ
r : ι → ℝ
F : ℝ → ℂ
s : ℂ
hs : 0 < s.re
hF : ∀ t ∈ Ioi 0, HasSum (fun i => if r i = 0 then 0 else a i * ↑(r i) * ↑(rexp (-π * r i ^ 2 * t))) (F t)
h_sum : Summable fun i => ‖a i‖ / |r i| ^ s.re
hs₁ : s ≠ 0
hs₂ : 0 < (s + 1).re
hs₃ : s + 1 ≠ 0
this :
  ∀ (i : ι) (t : ℝ),
    a i * ↑(r i) * ↑(rexp (-π * r i ^ 2 * t)) = if r i = 0 then 0 else a i * ↑(r i) * ↑(rexp (-π * r i ^ 2 * t))
i : ι
h : r i ≠ 0
⊢ ‖a i * ↑(r i)‖ / |r i| ^ (s + 1).re = ‖a i‖ / |r i| ^ s.re

Tactic:
rw [add_re, one_re, rpow_add (abs_pos.mpr h), rpow_one, norm_mul, norm_real,
  Real.norm_eq_abs, ← div_div, div_right_comm, mul_div_cancel_right₀ _ (abs_ne_zero.mpr h)]

Result:
no goals

Proof state:
case h.e'_5.h.inr
ι : Type u_1
inst✝ : Countable ι
a : ι → ℂ
r : ι → ℝ
F : ℝ → ℂ
s : ℂ
hs : 0 < s.re
hF : ∀ t ∈ Ioi 0, HasSum (fun i => if r i = 0 then 0 else a i * ↑(r i) * ↑(rexp (-π * r i ^ 2 * t))) (F t)
h_sum : Summable fun i => ‖a i‖ / |r i| ^ s.re
hs₁ : s ≠ 0
hs₂ : 0 < (s + 1).re
hs₃ : s + 1 ≠ 0
this :
  ∀ (i : ι) (t : ℝ),
    a i * ↑(r i) * ↑(rexp (-π * r i ^ 2 * t)) = if r i = 0 then 0 else a i * ↑(r i) * ↑(rexp (-π * r i ^ 2 * t))
i : ι
h : r i ≠ 0
⊢ (s + 1).Gammaℝ * a i * ↑(SignType.sign (r i)) / ↑|r i| ^ s = (s + 1).Gammaℝ * (a i * ↑(r i)) / (↑|r i| ^ s * ↑|r i|)

Tactic:
conv_rhs => enter [1]; rw [← sign_mul_abs (r i), ofReal_mul, ← ofRealHom_eq_coe,
  SignType.map_cast]

Result:
case h.e'_5.h.inr
ι : Type u_1
inst✝ : Countable ι
a : ι → ℂ
r : ι → ℝ
F : ℝ → ℂ
s : ℂ
hs : 0 < s.re
hF : ∀ t ∈ Ioi 0, HasSum (fun i => if r i = 0 then 0 else a i * ↑(r i) * ↑(rexp (-π * r i ^ 2 * t))) (F t)
h_sum : Summable fun i => ‖a i‖ / |r i| ^ s.re
hs₁ : s ≠ 0
hs₂ : 0 < (s + 1).re
hs₃ : s + 1 ≠ 0
this :
  ∀ (i : ι) (t : ℝ),
    a i * ↑(r i) * ↑(rexp (-π * r i ^ 2 * t)) = if r i = 0 then 0 else a i * ↑(r i) * ↑(rexp (-π * r i ^ 2 * t))
i : ι
h : r i ≠ 0
⊢ (s + 1).Gammaℝ * a i * ↑(SignType.sign (r i)) / ↑|r i| ^ s =
    (s + 1).Gammaℝ * (a i * (↑(SignType.sign (r i)) * ↑|r i|)) / (↑|r i| ^ s * ↑|r i|)

Proof state:
case h.e'_5.h
ι : Type u_1
inst✝ : Countable ι
a : ι → ℂ
r : ι → ℝ
F : ℝ → ℂ
s : ℂ
hs : 0 < s.re
hF : ∀ t ∈ Ioi 0, HasSum (fun i => if r i = 0 then 0 else a i * ↑(r i) * ↑(rexp (-π * r i ^ 2 * t))) (F t)
h_sum : Summable fun i => ‖a i‖ / |r i| ^ s.re
hs₁ : s ≠ 0
hs₂ : 0 < (s + 1).re
hs₃ : s + 1 ≠ 0
this :
  ∀ (i : ι) (t : ℝ),
    a i * ↑(r i) * ↑(rexp (-π * r i ^ 2 * t)) = if r i = 0 then 0 else a i * ↑(r i) * ↑(rexp (-π * r i ^ 2 * t))
i : ι
⊢ (s + 1).Gammaℝ * a i * ↑(SignType.sign (r i)) / ↑|r i| ^ s = (s + 1).Gammaℝ * (a i * ↑(r i)) / ↑|r i| ^ (s + 1)

Tactic:
rcases eq_or_ne (r i) 0 with h | h

Result:
case h.e'_5.h.inl
ι : Type u_1
inst✝ : Countable ι
a : ι → ℂ
r : ι → ℝ
F : ℝ → ℂ
s : ℂ
hs : 0 < s.re
hF : ∀ t ∈ Ioi 0, HasSum (fun i => if r i = 0 then 0 else a i * ↑(r i) * ↑(rexp (-π * r i ^ 2 * t))) (F t)
h_sum : Summable fun i => ‖a i‖ / |r i| ^ s.re
hs₁ : s ≠ 0
hs₂ : 0 < (s + 1).re
hs₃ : s + 1 ≠ 0
this :
  ∀ (i : ι) (t : ℝ),
    a i * ↑(r i) * ↑(rexp (-π * r i ^ 2 * t)) = if r i = 0 then 0 else a i * ↑(r i) * ↑(rexp (-π * r i ^ 2 * t))
i : ι
h : r i = 0
⊢ (s + 1).Gammaℝ * a i * ↑(SignType.sign (r i)) / ↑|r i| ^ s = (s + 1).Gammaℝ * (a i * ↑(r i)) / ↑|r i| ^ (s + 1)

case h.e'_5.h.inr
ι : Type u_1
inst✝ : Countable ι
a : ι → ℂ
r : ι → ℝ
F : ℝ → ℂ
s : ℂ
hs : 0 < s.re
hF : ∀ t ∈ Ioi 0, HasSum (fun i => if r i = 0 then 0 else a i * ↑(r i) * ↑(rexp (-π * r i ^ 2 * t))) (F t)
h_sum : Summable fun i => ‖a i‖ / |r i| ^ s.re
hs₁ : s ≠ 0
hs₂ : 0 < (s + 1).re
hs₃ : s + 1 ≠ 0
this :
  ∀ (i : ι) (t : ℝ),
    a i * ↑(r i) * ↑(rexp (-π * r i ^ 2 * t)) = if r i = 0 then 0 else a i * ↑(r i) * ↑(rexp (-π * r i ^ 2 * t))
i : ι
h : r i ≠ 0
⊢ (s + 1).Gammaℝ * a i * ↑(SignType.sign (r i)) / ↑|r i| ^ s = (s + 1).Gammaℝ * (a i * ↑(r i)) / ↑|r i| ^ (s + 1)

Proof state:
ι : Type u_1
inst✝ : Countable ι
a : ι → ℂ
r : ι → ℝ
F : ℝ → ℂ
s : ℂ
hs : 0 < s.re
hF : ∀ t ∈ Ioi 0, HasSum (fun i => a i * ↑(r i) * ↑(rexp (-π * r i ^ 2 * t))) (F t)
h_sum : Summable fun i => ‖a i‖ / |r i| ^ s.re
⊢ HasSum (fun i => (s + 1).Gammaℝ * a i * ↑(SignType.sign (r i)) / ↑|r i| ^ s) (mellin F ((s + 1) / 2))

Tactic:
have hs₁ : s ≠ 0 := fun h ↦ lt_irrefl _ (zero_re ▸ h ▸ hs)

Result:
ι : Type u_1
inst✝ : Countable ι
a : ι → ℂ
r : ι → ℝ
F : ℝ → ℂ
s : ℂ
hs : 0 < s.re
hF : ∀ t ∈ Ioi 0, HasSum (fun i => a i * ↑(r i) * ↑(rexp (-π * r i ^ 2 * t))) (F t)
h_sum : Summable fun i => ‖a i‖ / |r i| ^ s.re
hs₁ : s ≠ 0
⊢ HasSum (fun i => (s + 1).Gammaℝ * a i * ↑(SignType.sign (r i)) / ↑|r i| ^ s) (mellin F ((s + 1) / 2))