136 lines
5.0 KiB
Plaintext
136 lines
5.0 KiB
Plaintext
import Mathlib.Data.Fin.Tuple.Basic
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import Mathlib.Analysis.Complex.Basic
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import Mathlib.Analysis.Complex.TaylorSeries
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import Mathlib.Analysis.Calculus.LineDeriv.Basic
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import Mathlib.Analysis.Calculus.ContDiff.Defs
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import Mathlib.Analysis.Calculus.FDeriv.Basic
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import Mathlib.Analysis.Calculus.FDeriv.Symmetric
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import Mathlib.Data.Complex.Module
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import Mathlib.Data.Complex.Order
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import Mathlib.Data.Complex.Exponential
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import Mathlib.Analysis.RCLike.Basic
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import Mathlib.Order.Filter.Basic
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import Mathlib.Topology.Algebra.InfiniteSum.Module
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import Mathlib.Topology.Basic
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import Mathlib.Topology.Instances.RealVectorSpace
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import Nevanlinna.cauchyRiemann
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import Nevanlinna.partialDeriv
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variable {F : Type*} [NormedAddCommGroup F] [NormedSpace ℝ F]
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variable {G : Type*} [NormedAddCommGroup G] [NormedSpace ℝ G]
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noncomputable def Complex.laplace : (ℂ → F) → (ℂ → F) :=
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fun f ↦ partialDeriv ℝ 1 (partialDeriv ℝ 1 f) + partialDeriv ℝ Complex.I (partialDeriv ℝ Complex.I f)
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theorem laplace_add {f₁ f₂ : ℂ → F} (h₁ : ContDiff ℝ 2 f₁) (h₂ : ContDiff ℝ 2 f₂): Complex.laplace (f₁ + f₂) = (Complex.laplace f₁) + (Complex.laplace f₂) := by
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unfold Complex.laplace
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rw [partialDeriv_add₂]
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rw [partialDeriv_add₂]
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rw [partialDeriv_add₂]
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rw [partialDeriv_add₂]
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exact
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add_add_add_comm (partialDeriv ℝ 1 (partialDeriv ℝ 1 f₁))
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(partialDeriv ℝ 1 (partialDeriv ℝ 1 f₂))
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(partialDeriv ℝ Complex.I (partialDeriv ℝ Complex.I f₁))
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(partialDeriv ℝ Complex.I (partialDeriv ℝ Complex.I f₂))
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exact (partialDeriv_contDiff ℝ h₁ Complex.I).differentiable le_rfl
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exact (partialDeriv_contDiff ℝ h₂ Complex.I).differentiable le_rfl
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exact h₁.differentiable one_le_two
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exact h₂.differentiable one_le_two
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exact (partialDeriv_contDiff ℝ h₁ 1).differentiable le_rfl
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exact (partialDeriv_contDiff ℝ h₂ 1).differentiable le_rfl
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exact h₁.differentiable one_le_two
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exact h₂.differentiable one_le_two
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theorem laplace_smul {f : ℂ → F} (h : ContDiff ℝ 2 f) : ∀ v : ℝ, Complex.laplace (v • f) = v • (Complex.laplace f) := by
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intro v
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unfold Complex.laplace
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rw [partialDeriv_smul₂]
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rw [partialDeriv_smul₂]
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rw [partialDeriv_smul₂]
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rw [partialDeriv_smul₂]
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simp
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exact (partialDeriv_contDiff ℝ h Complex.I).differentiable le_rfl
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exact h.differentiable one_le_two
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exact (partialDeriv_contDiff ℝ h 1).differentiable le_rfl
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exact h.differentiable one_le_two
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theorem laplace_compContLin {f : ℂ → F} {l : F →L[ℝ] G} (h : ContDiff ℝ 2 f) :
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Complex.laplace (l ∘ f) = l ∘ (Complex.laplace f) := by
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unfold Complex.laplace
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rw [partialDeriv_compContLin]
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rw [partialDeriv_compContLin]
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rw [partialDeriv_compContLin]
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rw [partialDeriv_compContLin]
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simp
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exact (partialDeriv_contDiff ℝ h Complex.I).differentiable le_rfl
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exact h.differentiable one_le_two
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exact (partialDeriv_contDiff ℝ h 1).differentiable le_rfl
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exact h.differentiable one_le_two
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theorem laplace_compContLinAt {f : ℂ → F} {l : F →L[ℝ] G} {x : ℂ} (h : ContDiffAt ℝ 2 f x) :
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Complex.laplace (l ∘ f) x = (l ∘ (Complex.laplace f)) x := by
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have A₂ : ∃ v ∈ nhds x, (IsOpen v) ∧ (x ∈ v) ∧ (ContDiffOn ℝ 2 f v) := by
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have : ∃ u ∈ nhds x, ContDiffOn ℝ 2 f u := by
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apply ContDiffAt.contDiffOn h
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rfl
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obtain ⟨u, hu₁, hu₂⟩ := this
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obtain ⟨v, hv₁, hv₂, hv₃⟩ := mem_nhds_iff.1 hu₁
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use v
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constructor
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· exact IsOpen.mem_nhds hv₂ hv₃
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· constructor
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exact hv₂
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constructor
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· exact hv₃
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· exact ContDiffOn.congr_mono hu₂ (fun x => congrFun rfl) hv₁
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obtain ⟨v, hv₁, hv₂, hv₃, hv₄⟩ := A₂
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have D : ∀ w : ℂ, partialDeriv ℝ w (l ∘ f) =ᶠ[nhds x] l ∘ partialDeriv ℝ w (f) := by
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intro w
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apply Filter.eventuallyEq_iff_exists_mem.2
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use v
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constructor
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· exact IsOpen.mem_nhds hv₂ hv₃
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· intro y hy
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apply partialDeriv_compContLinAt
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let V := ContDiffOn.differentiableOn hv₄ one_le_two
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apply DifferentiableOn.differentiableAt V
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apply IsOpen.mem_nhds
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assumption
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assumption
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unfold Complex.laplace
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simp
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rw [partialDeriv_eventuallyEq ℝ (D 1) 1]
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rw [partialDeriv_compContLinAt]
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rw [partialDeriv_eventuallyEq ℝ (D Complex.I) Complex.I]
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rw [partialDeriv_compContLinAt]
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simp
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-- DifferentiableAt ℝ (partialDeriv ℝ Complex.I f) x
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apply ContDiffAt.differentiableAt (partialDeriv_contDiffAt ℝ (ContDiffOn.contDiffAt hv₄ hv₁) Complex.I)
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rfl
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-- DifferentiableAt ℝ (partialDeriv ℝ 1 f) x
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apply ContDiffAt.differentiableAt (partialDeriv_contDiffAt ℝ (ContDiffOn.contDiffAt hv₄ hv₁) 1)
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rfl
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theorem laplace_compCLE {f : ℂ → F} {l : F ≃L[ℝ] G} (h : ContDiff ℝ 2 f) :
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Complex.laplace (l ∘ f) = l ∘ (Complex.laplace f) := by
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let l' := (l : F →L[ℝ] G)
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have : Complex.laplace (l' ∘ f) = l' ∘ (Complex.laplace f) := by
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exact laplace_compContLin h
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exact this
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