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Project-declaredLean 4.31.0 · mathlib@fabf563a7c95

Θ₂ term imag axis re

Θ₂_term_imag_axis_re

Plain-language statement

Each term Θ₂_term n (I*t) has positive real part equal to exp(-π(n+1/2)²t) for t > 0.

Exact Lean statement

lemma Θ₂_term_imag_axis_re (n : ℤ) (t : ℝ) (ht : 0 < t) :
    (Θ₂_term n ⟨I * t, by simp [ht]⟩).re =
      Real.exp (-Real.pi * ((n : ℝ) + 1/2) ^ 2 * t)

Formal artifact

Lean source

Canonical source
Full Lean sourceLean 4
lemma Θ₂_term_imag_axis_re (n : ) (t : ) (ht : 0 < t) :    (Θ₂_term n I * t, by simp [ht]).re =      Real.exp (-Real.pi * ((n : ) + 1/2) ^ 2 * t) := by  unfold Θ₂_term  change (cexp (Real.pi * I * ((n : ℂ) + 1 / 2) ^ 2 * (I * t))).re = _  have hexpr : Real.pi * I * ((n : ℂ) + 1 / 2) ^ 2 * (I * ↑t) =      (-(Real.pi * ((n : ) + 1/2) ^ 2 * t) : ) := by    have hI : I ^ 2 = -1 := I_sq    push_cast    ring_nf    simp only [hI]    ring  rw [hexpr]  rw [Complex.exp_ofReal_re]  ring_nf
Project
Sphere Packing in Dimension 8
License
Apache-2.0
Commit
acfc6204e65a
Source
SpherePacking/ModularForms/JacobiTheta/Basic.lean:694-708

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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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