| import Mathlib | |
| namespace OAI | |
| namespace InvariantProjection.FiniteConvolution | |
| abbrev Coefficients (K : ℕ) := Fin (2 * K + 1) → ℂ | |
| def center (K : ℕ) : Fin (2 * K + 1) := ⟨K, by omega⟩ | |
| noncomputable def polynomial {K : ℕ} (a : Coefficients K) : Polynomial ℂ := | |
| ∑ i : Fin (2 * K + 1), Polynomial.monomial (i : ℕ) (a i) | |
| noncomputable def lowProduct {K : ℕ} (a b : Coefficients K) : Coefficients K := | |
| fun n => (polynomial a * polynomial b).coeff (n : ℕ) | |
| end InvariantProjection.FiniteConvolution | |
| end OAI | |