OAI/Geometry/SurfaceImmersion/Primitive/PeriodicBumpAverage.lean

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Localized positive periodic densities approximate any chosen path value.

  1. theorem OAI.ClosedSurfaceR4.LoopDensity.exists_bump_average_near line 16

    Source documentation

    Point masses in the convex-hull argument can be replaced by actual smooth nonnegative densities while changing their vector moments arbitrarily little.

    theorem exists_bump_average_near {f : ℝ → E} (hf : Continuous f)
        {c ε : ℝ} (hc : c ∈ Ioo (0 : ℝ) 1) (hε : 0 < ε) :
        ∃ ψ : ℝ → ℝ, ContDiff ℝ ∞ ψ ∧ Function.Periodic ψ 1 ∧
          (∀ t, 0 ≤ ψ t) ∧ (∫ t in 0..1, ψ t) = 1 ∧
          ‖(∫ t in 0..1, ψ t • f t) - f c‖ < ε := by
    …