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LeanPool.NavierStokesAndEuler.Euler.AngleMeanZeroPrimitive

The actual mean-zero periodic angular primitive #

This is an explicit Bochner integral, valid also for a Hilbert-valued angle curve such as a time-L² pressure coefficient. Periodicity is proved from the zero integral of the forcing; subtracting the actual mean fixes the constant.

noncomputable def EulerAngleMeanZeroPrimitive.rawPrimitive {E : Type u_1} [NormedAddCommGroup E] [NormedSpace E] (f : E) (θ : ) :
E

The raw angular primitive, anchored at angle zero.

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    noncomputable def EulerAngleMeanZeroPrimitive.primitive {E : Type u_1} [NormedAddCommGroup E] [NormedSpace E] (P : ) (f : E) (θ : ) :
    E

    The actual angular primitive with its mean over one period removed.

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      The explicit integral has the actual derivative prescribed by the forcing.

      The raw angular primitive is continuous.

      theorem EulerAngleMeanZeroPrimitive.primitive_hasDerivAt {E : Type u_1} [NormedAddCommGroup E] [NormedSpace E] [CompleteSpace E] (P : ) (f : E) (hf : Continuous f) (θ : ) :
      HasDerivAt (primitive P f) (f θ) θ

      Removing the mean does not change the actual angular derivative.

      The normalized angular primitive is continuous.

      theorem EulerAngleMeanZeroPrimitive.rawPrimitive_periodic {E : Type u_1} [NormedAddCommGroup E] [NormedSpace E] (P : ) (f : E) (hf : Continuous f) (hper : Function.Periodic f P) (hmean : (θ : ) in 0..P, f θ = 0) :

      Zero angular mean of the forcing makes the raw integral periodic.

      theorem EulerAngleMeanZeroPrimitive.primitive_periodic {E : Type u_1} [NormedAddCommGroup E] [NormedSpace E] (P : ) (f : E) (hf : Continuous f) (hper : Function.Periodic f P) (hmean : (θ : ) in 0..P, f θ = 0) :

      The normalized angular primitive is genuinely periodic.

      theorem EulerAngleMeanZeroPrimitive.primitive_mean_zero {E : Type u_1} [NormedAddCommGroup E] [NormedSpace E] [CompleteSpace E] (P : ) (hP : P 0) (f : E) (hf : Continuous f) :
      (θ : ) in 0..P, primitive P f θ = 0

      The normalization gives exactly zero integral over one angular period.

      theorem EulerAngleMeanZeroPrimitive.primitive_unique {E : Type u_1} [NormedAddCommGroup E] [NormedSpace E] [CompleteSpace E] (P : ) (hP : P 0) (f : E) (hf : Continuous f) (g : E) (hg : ∀ (θ : ), HasDerivAt g (f θ) θ) (hmean : (θ : ) in 0..P, g θ = 0) :
      g = primitive P f

      The zero-mean angular primitive is unique among genuine differentiable primitives.