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Project-declaredLean 4.31.0 · mathlib@fabf563a7c95

Deriv Fmod GReal

deriv_FmodGReal

Plain-language statement

The derivative of FmodGReal is (-2π) * L₁,₀(it) / G(it)².

Exact Lean statement

theorem deriv_FmodGReal (t : ℝ) (ht : 0 < t) :
    deriv FmodGReal t = (-2 * π) * (L₁₀ ⟨Complex.I * t, by simp [ht]⟩).re /
      (G ⟨Complex.I * t, by simp [ht]⟩).re ^ 2

Formal artifact

Lean source

Canonical source
Full Lean sourceLean 4
theorem deriv_FmodGReal (t : ) (ht : 0 < t) :    deriv FmodGReal t = (-2 * π) * (L₁₀ Complex.I * t, by simp [ht]).re /      (G Complex.I * t, by simp [ht]).re ^ 2 := by  set z : ℍ := Complex.I * t, by simp [ht] with hz_def  have hF_deriv := hasDerivAt_resToImagAxis_re F_holo ht  have hG_deriv := hasDerivAt_resToImagAxis_re G_holo ht  have hG_pos : 0 < (G z).re := by simpa [ResToImagAxis, ht] using G_imag_axis_pos.2 t ht  have hG_ne : (G.resToImagAxis t).re  0 := by    simpa [ResToImagAxis, ht, hz_def] using ne_of_gt hG_pos  have heq : FmodGReal =ᶠ[nhds t]      (fun s => (F.resToImagAxis s).re / (G.resToImagAxis s).re) := by    filter_upwards [lt_mem_nhds ht] with s hs    simp only [FmodGReal, FReal, GReal, Function.resToImagAxis_apply, ResToImagAxis,      hs, ↓reduceDIte]  rw [heq.deriv_eq]  have hdiv : deriv (fun s  (F.resToImagAxis s).re / (G.resToImagAxis s).re) t =      (deriv (fun s  (F.resToImagAxis s).re) t * (G.resToImagAxis t).re -        (F.resToImagAxis t).re * deriv (fun s  (G.resToImagAxis s).re) t) /          (G.resToImagAxis t).re ^ 2 :=    deriv_div hF_deriv.differentiableAt hG_deriv.differentiableAt hG_ne  rw [hdiv, hF_deriv.deriv, hG_deriv.deriv]  simp only [Function.resToImagAxis_apply, ResToImagAxis, ht, ↓reduceDIte, hz_def]  have hF_real := F_imag_axis_real t ht  have hG_real := G_imag_axis_real t ht  simp only [Function.resToImagAxis_apply, ResToImagAxis, ht, ↓reduceDIte] at hF_real hG_real  have hL₁₀ := L₁₀_eq_FD_G_sub_F_DG z  simp only [hz_def] at hL₁₀ hF_real hG_real  rw [hL₁₀]  simp only [mul_re, sub_re, hF_real, hG_real, mul_zero, sub_zero, zero_mul]  ring
Project
Sphere Packing in Dimension 8
License
Apache-2.0
Commit
acfc6204e65a
Source
SpherePacking/ModularForms/FG.lean:981-1010

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Related declarations

Project-declaredLean 4.31.0

Anti Der Pos

antiDerPos

Plain-language statement

If FF is a modular form where F(it)F(it) is positive for sufficiently large tt (i.e. constant term is positive) and the derivative is positive, then FF is also positive.

sphere packingFourier analysismodular forms

Source project: Sphere Packing in Dimension 8

Person-level attribution pending.

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Project-declaredLean 4.31.0

Anti Serre Der Pos

antiSerreDerPos

Plain-language statement

Let F:HCF : \mathbb{H} \to \mathbb{C} be a holomorphic function where F(it)F(it) is real for all t>0t > 0. Assume that Serre derivative kF\partial_k F is positive on the imaginary axis. If F(it)F(it) is positive for sufficiently large tt, then F(it)F(it) is positive for all t>0t > 0.

sphere packingFourier analysismodular forms

Source project: Sphere Packing in Dimension 8

Person-level attribution pending.

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