OAI/NumberTheory/Ostmann/Characters/CRTFourier.lean
6 declarations, 0 contain sorry, 0 declared as axioms
Chinese remainder factorization of the finite Fourier transform
- theorem
OAI.Ostmann.stdAddChar_mul_factorline 11 - theorem
OAI.Ostmann.crt_fstline 26 - theorem
OAI.Ostmann.crt_sndline 32 - theorem
OAI.Ostmann.crt_stdAddCharline 38 - theorem
OAI.Ostmann.additiveFourier_crtline 86Source documentation
Probability normalization makes the coprime Fourier transform a product.
theorem additiveFourier_crt {m n : ℕ} [NeZero m] [NeZero n] (h : m.Coprime n) (f : ZMod m → ℂ) (g : ZMod n → ℂ) (u : ZMod (m * n)) : additiveFourier (fun x => f ((ZMod.chineseRemainder h) x).1 * g ((ZMod.chineseRemainder h) x).2) u = additiveFourier f ((n : ZMod m)⁻¹ * ((ZMod.chineseRemainder h) u).1) * additiveFourier g ((m : ZMod n)⁻¹ * ((ZMod.chineseRemainder h) u).2) := by …Mentions: OAI.Ostmann.additiveFourier
- theorem
OAI.Ostmann.additiveFourier_translateline 122Source documentation
Translation contributes its additive character with the negative Fourier sign.
theorem additiveFourier_translate {N : ℕ} [NeZero N] (f : ZMod N → ℂ) (t u : ZMod N) : additiveFourier (fun x => f (x - t)) u = ZMod.stdAddChar (-(t * u)) * additiveFourier f u := by …Mentions: OAI.Ostmann.additiveFourier