Norm oscillatory integral le integral deriv div abs
norm_oscillatory_integral_le_integral_deriv_div_abs
Plain-language statement
The |T| variant of the oscillatory-integral decay bound: for T ≠ 0, ‖∫ g y · exp(T·i·y)‖ ≤ (∫ ‖deriv g x‖) / |T|.
Exact Lean statement
lemma norm_oscillatory_integral_le_integral_deriv_div_abs
(g : ℝ → ℂ) (hg : Integrable g) (hdiff : Differentiable ℝ g)
(hg' : Integrable (deriv g)) {T : ℝ} (hT : T ≠ 0) :
‖∫ y, g y * exp ((T : ℂ) * Complex.I * (y : ℂ)) ∂volume‖ ≤
(∫ x, ‖deriv g x‖ ∂volume) / |T|Formal artifact
Lean source
lemma norm_oscillatory_integral_le_integral_deriv_div_abs (g : ℝ → ℂ) (hg : Integrable g) (hdiff : Differentiable ℝ g) (hg' : Integrable (deriv g)) {T : ℝ} (hT : T ≠ 0) : ‖∫ y, g y * exp ((T : ℂ) * Complex.I * (y : ℂ)) ∂volume‖ ≤ (∫ x, ‖deriv g x‖ ∂volume) / |T| := by have hw : -T / (2 * Real.pi) ≠ 0 := by exact div_ne_zero (neg_ne_zero.mpr hT) (mul_ne_zero two_ne_zero Real.pi_ne_zero) have hfourier := norm_fourier_le_integral_deriv_div g hg hdiff hg' hw have heq : (∫ y, g y * exp ((T : ℂ) * Complex.I * (y : ℂ)) ∂volume) = 𝓕 g (-T / (2 * Real.pi)) := by rw [Real.fourier_real_eq_integral_exp_smul] apply integral_congr_ae filter_upwards with y rw [smul_eq_mul] rw [mul_comm (g y)] congr 1 congr 1 push_cast field_simp [Real.pi_ne_zero] rw [heq] refine hfourier.trans_eq ?_ congr 1 have hden : (2 * Real.pi) * |-T / (2 * Real.pi)| = |T| := by have htwopi_pos : 0 < 2 * Real.pi := by positivity rw [abs_div, abs_neg, abs_of_pos htwopi_pos] field_simp [Real.pi_ne_zero] rw [hden]- Project
- Prime Number Theorem and More
- License
- Apache-2.0
- Commit
- a93551347dce
- Source
- PrimeNumberTheoremAnd/Fourier.lean:159-186
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Source project: Prime Number Theorem and More
Person-level attribution pending.