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AlexKontorovich/PrimeNumberTheoremAnd
Source indexedtheorem · leanprover/lean4:v4.32.0

Complex.Hadamard.EntireOfOrderAtMost.comp_add_const

PrimeNumberTheoremAnd.Mathlib.Analysis.Complex.HadamardFactorization.Order · PrimeNumberTheoremAnd/Mathlib/Analysis/Complex/HadamardFactorization/Order.lean:119 to 150

Source documentation

Finite order is invariant under translation of the input.

Exact Lean statement

theorem comp_add_const {ρ : ℝ} {f : ℂ → ℂ} (h : EntireOfOrderAtMost ρ f)
    (hρ : 0 ≤ ρ) (c : ℂ) :
    EntireOfOrderAtMost ρ (fun z : ℂ => f (z + c))

Complete declaration

Lean source

Canonical source
Full Lean sourceLean 4
theorem comp_add_const {ρ : } {f : ℂ  ℂ} (h : EntireOfOrderAtMost ρ f)    (hρ : 0  ρ) (c : ℂ) :    EntireOfOrderAtMost ρ (fun z : ℂ => f (z + c)) := by  refine h.differentiable.comp (differentiable_id.add (differentiable_const c)), ?_  intro ε hε  rcases h.exists_boundwith C, hC, hCbound  let A :  := 1 + ‖c‖  let C' :  := C * A ^+ ε)  have hApos : 0 < A := by    dsimp [A]    positivity  have hτnonneg : 0  ρ + ε := by linarith  refine C', mul_pos hC (Real.rpow_pos_of_pos hApos _), ?_  intro z  have hbase :      1 + ‖z + c‖  A * (1 + ‖z‖) := by    dsimp [A]    have hnorm : ‖z + c‖  ‖z‖ + ‖c‖ := norm_add_le z c    nlinarith [norm_nonneg z, norm_nonneg c]  have hpow :      (1 + ‖z + c‖) ^+ ε)  (A * (1 + ‖z‖)) ^+ ε) := by    exact Real.rpow_le_rpow (by positivity) hbase hτnonneg  calc    ‖f (z + c)‖  Real.exp (C * (1 + ‖z + c‖) ^+ ε)) := hCbound (z + c)    _  Real.exp (C' * (1 + ‖z‖) ^+ ε)) := by      refine Real.exp_le_exp.2 ?_      calc        C * (1 + ‖z + c‖) ^+ ε)  C * (A * (1 + ‖z‖)) ^+ ε) := by          exact mul_le_mul_of_nonneg_left hpow hC.le        _ = C' * (1 + ‖z‖) ^+ ε) := by          rw [Real.mul_rpow (le_of_lt hApos) (by positivity : 0  1 + ‖z‖)]          ring