OAI/Geometry/EinsteinFour/JacobiDirichletPositivity.lean

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Positive Jacobi pivot ratios give the actual finite curvature matrix.

  1. theorem OAI.PositiveEinsteinFour.Jacobi.curvatureDirichlet_posDef_of_ratios line 16

    Source documentation

    The positive ratios are the ordered Schur pivots of the concrete curvature Dirichlet matrix. No commutation between time samples is used.

    theorem curvatureDirichlet_posDef_of_ratios {N : ℕ} {t : ℝ} (ht : t ≠ 0)
        (R : ℕ → NormalMatrix)
        (hunit : ∀ i, 1 ≤ i → i ≤ N + 1 →
          IsUnit (normalizedDiscrete R (t / (N + 1)) i).det)
        (hpos : ∀ i, 1 ≤ i → i ≤ N →
          (normalizedDiscrete R (t / (N + 1)) (i + 1) *
            (normalizedDiscrete R (t / (N + 1)) i)⁻¹).PosDef) :
        (curvatureDirichlet t (fun i : Fin N => R (i.val + 1) - 1)).PosDef := by
    …

    Mentions: OAI.PositiveEinsteinFour.Jacobi.NormalMatrix, OAI.PositiveEinsteinFour.Jacobi.normalizedDiscrete, OAI.PositiveEinsteinFour.Jacobi.curvatureDirichlet