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Project-declaredLean 4.31.0 · mathlib@fabf563a7c95

Modular form tendsto at Im Infty

modular_form_tendsto_atImInfty

Plain-language statement

A modular form tends to its value at infinity as z → i∞.

Exact Lean statement

lemma modular_form_tendsto_atImInfty {k : ℤ} (f : ModularForm (Gamma 1) k) :
    Filter.Tendsto f.toFun atImInfty (nhds ((qExpansion 1 f).coeff 0))

Formal artifact

Lean source

Canonical source
Full Lean sourceLean 4
lemma modular_form_tendsto_atImInfty {k : } (f : ModularForm (Gamma 1) k) :    Filter.Tendsto f.toFun atImInfty (nhds ((qExpansion 1 f).coeff 0)) := by  obtain c, hc, hO := ModularFormClass.exp_decay_sub_atImInfty' f  have hΓ : (1 : )  (↑(CongruenceSubgroup.Gamma 1) : Subgroup (GL (Fin 2) )).strictPeriods :=    CongruenceSubgroup.Gamma_one_coe_eq_SL ▸ one_mem_strictPeriods_SL  rw [qExpansion_coeff_zero (by norm_num : (0 : ) < 1)    (ModularFormClass.analyticAt_cuspFunction_zero f (by norm_num) hΓ)    (periodic_comp_ofComplex f hΓ)]  simpa using (tendsto_zero_of_exp_decay hc hO).add_const (valueAtInfty f.toFun)
Project
Sphere Packing in Dimension 8
License
Apache-2.0
Commit
acfc6204e65a
Source
SpherePacking/ModularForms/EisensteinAsymptotics.lean:54-62

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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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