OAI/NumberTheory/Ostmann/QuadraticCenter/SmallKernelQuadraticSum.lean
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The uniform small-kernel bound for a weighted quadratic sum
- theorem
OAI.Ostmann.small_kernel_quadratic_sum_boundline 14Source documentation
The cutoff may include a complex quadratic phase. Only its absolute bound enters this estimate, while the interval covers at least one period.
theorem small_kernel_quadratic_sum_bound (q W : ℕ) [NeZero q] (g : ZMod q → ℂ) (hg : ∀ x, ¬IsUnit x → g x = 0) (henergy : (∑ x : ZMod q, ‖g x‖ ^ 2) ≤ q) (a : ZMod q) (weight : ℕ → ℂ) (B C N : ℝ) (hB : 0 ≤ B) (hN : 0 < N) (hq : (q : ℝ) ≤ N) (hW : (W : ℝ) ≤ C * N) (hw : ∀ w ∈ Finset.Ioc 0 W, ‖weight w‖ ≤ B) : ‖(N : ℂ)⁻¹ * ∑ w ∈ Finset.Ioc 0 W, g (a * (w : ZMod q) ^ 2) * weight w‖ ≤ B * (C + 1) * Real.sqrt ((2 : ℝ) ^ (q.primeFactors.card + 1)) := by …