diff --git a/Nevanlinna/specialFunctions_CircleIntegral_affine.lean b/Nevanlinna/specialFunctions_CircleIntegral_affine.lean index 891bdfc..fae2a66 100644 --- a/Nevanlinna/specialFunctions_CircleIntegral_affine.lean +++ b/Nevanlinna/specialFunctions_CircleIntegral_affine.lean @@ -8,275 +8,6 @@ open Real Filter MeasureTheory intervalIntegral -lemma logsinBound : ∀ x ∈ (Set.Icc 0 1), ‖(log ∘ sin) x‖ ≤ ‖log ((π / 2)⁻¹ * x)‖ := by - - intro x hx - by_cases h'x : x = 0 - · rw [h'x]; simp - - -- Now handle the case where x ≠ 0 - have l₀ : log ((π / 2)⁻¹ * x) ≤ 0 := by - apply log_nonpos - apply mul_nonneg - apply le_of_lt - apply inv_pos.2 - apply div_pos - exact pi_pos - exact zero_lt_two - apply (Set.mem_Icc.1 hx).1 - simp - apply mul_le_one - rw [div_le_one pi_pos] - exact two_le_pi - exact (Set.mem_Icc.1 hx).1 - exact (Set.mem_Icc.1 hx).2 - - have l₁ : 0 ≤ sin x := by - apply sin_nonneg_of_nonneg_of_le_pi (Set.mem_Icc.1 hx).1 - trans (1 : ℝ) - exact (Set.mem_Icc.1 hx).2 - trans π / 2 - exact one_le_pi_div_two - norm_num [pi_nonneg] - have l₂ : log (sin x) ≤ 0 := log_nonpos l₁ (sin_le_one x) - - simp only [norm_eq_abs, Function.comp_apply] - rw [abs_eq_neg_self.2 l₀] - rw [abs_eq_neg_self.2 l₂] - simp only [neg_le_neg_iff, ge_iff_le] - - have l₃ : x ∈ (Set.Ioi 0) := by - simp - exact lt_of_le_of_ne (Set.mem_Icc.1 hx).1 ( fun a => h'x (id (Eq.symm a)) ) - - have l₅ : 0 < (π / 2)⁻¹ * x := by - apply mul_pos - apply inv_pos.2 - apply div_pos pi_pos zero_lt_two - exact l₃ - - have : ∀ x ∈ (Set.Icc 0 (π / 2)), (π / 2)⁻¹ * x ≤ sin x := by - intro x hx - - have i₀ : 0 ∈ Set.Icc 0 π := - Set.left_mem_Icc.mpr pi_nonneg - have i₁ : π / 2 ∈ Set.Icc 0 π := - Set.mem_Icc.mpr ⟨div_nonneg pi_nonneg zero_le_two, half_le_self pi_nonneg⟩ - - have i₂ : 0 ≤ 1 - (π / 2)⁻¹ * x := by - rw [sub_nonneg] - calc (π / 2)⁻¹ * x - _ ≤ (π / 2)⁻¹ * (π / 2) := by - apply mul_le_mul_of_nonneg_left - exact (Set.mem_Icc.1 hx).2 - apply inv_nonneg.mpr (div_nonneg pi_nonneg zero_le_two) - _ = 1 := by - apply inv_mul_cancel - apply div_ne_zero_iff.mpr - constructor - · exact pi_ne_zero - · exact Ne.symm (NeZero.ne' 2) - - have i₃ : 0 ≤ (π / 2)⁻¹ * x := by - apply mul_nonneg - apply inv_nonneg.2 - apply div_nonneg - exact pi_nonneg - exact zero_le_two - exact (Set.mem_Icc.1 hx).1 - - have i₄ : 1 - (π / 2)⁻¹ * x + (π / 2)⁻¹ * x = 1 := by ring - - let B := strictConcaveOn_sin_Icc.concaveOn.2 i₀ i₁ i₂ i₃ i₄ - simp [Real.sin_pi_div_two] at B - rw [(by ring_nf; rw [mul_inv_cancel pi_ne_zero, one_mul] : 2 / π * x * (π / 2) = x)] at B - simpa - - apply log_le_log l₅ - apply this - apply Set.mem_Icc.mpr - constructor - · exact le_of_lt l₃ - · trans 1 - exact (Set.mem_Icc.1 hx).2 - exact one_le_pi_div_two - - -lemma intervalIntegrable_log_sin₁ : IntervalIntegrable (log ∘ sin) volume 0 1 := by - - have int_log : IntervalIntegrable (fun x ↦ ‖log x‖) volume 0 1 := by - apply IntervalIntegrable.norm - rw [← neg_neg log] - apply IntervalIntegrable.neg - apply intervalIntegrable_deriv_of_nonneg (g := fun x ↦ -(x * log x - x)) - · exact (continuous_mul_log.continuousOn.sub continuous_id.continuousOn).neg - · intro x hx - norm_num at hx - convert ((hasDerivAt_mul_log hx.left.ne.symm).sub (hasDerivAt_id x)).neg using 1 - norm_num - · intro x hx - norm_num at hx - rw [Pi.neg_apply, Left.nonneg_neg_iff] - exact (log_nonpos_iff hx.left).mpr hx.right.le - - - have int_log : IntervalIntegrable (fun x ↦ ‖log ((π / 2)⁻¹ * x)‖) volume 0 1 := by - - have A := IntervalIntegrable.comp_mul_right int_log (π / 2)⁻¹ - simp only [norm_eq_abs] at A - conv => - arg 1 - intro x - rw [mul_comm] - simp only [norm_eq_abs] - apply IntervalIntegrable.mono A - simp - trans Set.Icc 0 (π / 2) - exact Set.Icc_subset_Icc (Preorder.le_refl 0) one_le_pi_div_two - exact Set.Icc_subset_uIcc - exact Preorder.le_refl volume - - apply IntervalIntegrable.mono_fun' (g := fun x ↦ ‖log ((π / 2)⁻¹ * x)‖) - exact int_log - - -- AEStronglyMeasurable (log ∘ sin) (volume.restrict (Ι 0 1)) - apply ContinuousOn.aestronglyMeasurable - apply ContinuousOn.comp (t := Ι 0 1) - apply ContinuousOn.mono (s := {0}ᶜ) - exact continuousOn_log - intro x hx - by_contra contra - simp at contra - rw [contra, Set.left_mem_uIoc] at hx - linarith - exact continuousOn_sin - - -- Set.MapsTo sin (Ι 0 1) (Ι 0 1) - rw [Set.uIoc_of_le (zero_le_one' ℝ)] - exact fun x hx ↦ ⟨sin_pos_of_pos_of_le_one hx.1 hx.2, sin_le_one x⟩ - - -- MeasurableSet (Ι 0 1) - exact measurableSet_uIoc - - -- (fun x => ‖(log ∘ sin) x‖) ≤ᶠ[ae (volume.restrict (Ι 0 1))] ‖log‖ - dsimp [EventuallyLE] - rw [MeasureTheory.ae_restrict_iff] - apply MeasureTheory.ae_of_all - intro x hx - have : x ∈ Set.Icc 0 1 := by - simp - simp at hx - constructor - · exact le_of_lt hx.1 - · exact hx.2 - let A := logsinBound x this - simp only [Function.comp_apply, norm_eq_abs] at A - exact A - - apply measurableSet_le - apply Measurable.comp' - exact continuous_abs.measurable - exact Measurable.comp' measurable_log continuous_sin.measurable - -- Measurable fun a => |log ((π / 2)⁻¹ * a)| - apply Measurable.comp' - exact continuous_abs.measurable - apply Measurable.comp' - exact measurable_log - exact measurable_const_mul (π / 2)⁻¹ - -lemma intervalIntegrable_log_sin₂ : IntervalIntegrable (log ∘ sin) volume 0 (π / 2) := by - - apply IntervalIntegrable.trans (b := 1) - exact intervalIntegrable_log_sin₁ - - -- IntervalIntegrable (log ∘ sin) volume 1 (π / 2) - apply ContinuousOn.intervalIntegrable - apply ContinuousOn.comp continuousOn_log continuousOn_sin - intro x hx - rw [Set.uIcc_of_le, Set.mem_Icc] at hx - have : 0 < sin x := by - apply Real.sin_pos_of_pos_of_lt_pi - · calc 0 - _ < 1 := Real.zero_lt_one - _ ≤ x := hx.1 - · calc x - _ ≤ π / 2 := hx.2 - _ < π := div_two_lt_of_pos pi_pos - by_contra h₁x - simp at h₁x - rw [h₁x] at this - simp at this - exact one_le_pi_div_two - -lemma intervalIntegrable_log_sin : IntervalIntegrable (log ∘ sin) volume 0 π := by - apply IntervalIntegrable.trans (b := π / 2) - exact intervalIntegrable_log_sin₂ - let A := IntervalIntegrable.comp_sub_left intervalIntegrable_log_sin₂ π - simp at A - let B := IntervalIntegrable.symm A - have : π - π / 2 = π / 2 := by linarith - rwa [this] at B - -lemma intervalIntegrable_log_cos : IntervalIntegrable (log ∘ cos) volume 0 (π / 2) := by - let A := IntervalIntegrable.comp_sub_left intervalIntegrable_log_sin₂ (π / 2) - simp only [Function.comp_apply, sub_zero, sub_self] at A - simp_rw [sin_pi_div_two_sub] at A - have : (fun x => log (cos x)) = log ∘ cos := rfl - apply IntervalIntegrable.symm - rwa [← this] - - -lemma integral_log_sin : ∫ (x : ℝ) in (0)..(π / 2), log (sin x) = -log 2 * π/2 := by - - have t₀ {x : ℝ} : sin (2 * x) = 2 * sin x * cos x := sin_two_mul x - - have t₁ {x : ℝ} : log (sin (2 * x)) = log 2 + log (sin x) + log (cos x) := by - rw [sin_two_mul x, log_mul, log_mul] - exact Ne.symm (NeZero.ne' 2) - sorry - sorry - sorry - - have t₂ {x : ℝ} : log (sin x) = log (sin (2 * x)) - log 2 - log (cos x) := by - rw [t₁] - ring - - conv => - left - arg 1 - intro x - rw [t₂] - - rw [intervalIntegral.integral_sub, intervalIntegral.integral_sub] - rw [intervalIntegral.integral_const] - rw [intervalIntegral.integral_comp_mul_left (c := 2) (f := fun x ↦ log (sin x))] - simp - have : 2 * (π / 2) = π := by linarith - rw [this] - - have : ∫ (x : ℝ) in (0)..π, log (sin x) = 2 * ∫ (x : ℝ) in (0)..(π / 2), log (sin x) := by - sorry - rw [this] - have : ∫ (x : ℝ) in (0)..(π / 2), log (sin x) = ∫ (x : ℝ) in (0)..(π / 2), log (cos x) := by - sorry - rw [← this] - simp - linarith - - exact Ne.symm (NeZero.ne' 2) - -- IntervalIntegrable (fun x => log (sin (2 * x))) volume 0 (π / 2) - sorry - -- IntervalIntegrable (fun x => log 2) volume 0 (π / 2) - simp - -- IntervalIntegrable (fun x => log (sin (2 * x)) - log 2) volume 0 (π / 2) - apply IntervalIntegrable.sub - -- -- IntervalIntegrable (fun x => log (sin (2 * x))) volume 0 (π / 2) - sorry - -- -- IntervalIntegrable (fun x => log 2) volume 0 (π / 2) - simp - -- -- IntervalIntegrable (fun x => log (cos x)) volume 0 (π / 2) - exact intervalIntegrable_log_cos - lemma int₁₁ : ∫ (x : ℝ) in (0)..π, log (4 * sin x ^ 2) = 0 := by sorry diff --git a/Nevanlinna/specialFunctions_Integral_log.lean b/Nevanlinna/specialFunctions_Integral_log.lean index 92dcdc4..9b8eaae 100644 --- a/Nevanlinna/specialFunctions_Integral_log.lean +++ b/Nevanlinna/specialFunctions_Integral_log.lean @@ -9,224 +9,6 @@ open Real Filter MeasureTheory intervalIntegral -- The following theorem was suggested by Gareth Ma on Zulip -lemma logsinBound : ∀ x ∈ (Set.Icc 0 1), ‖(log ∘ sin) x‖ ≤ ‖log ((π / 2)⁻¹ * x)‖ := by - - intro x hx - by_cases h'x : x = 0 - · rw [h'x]; simp - - -- Now handle the case where x ≠ 0 - have l₀ : log ((π / 2)⁻¹ * x) ≤ 0 := by - apply log_nonpos - apply mul_nonneg - apply le_of_lt - apply inv_pos.2 - apply div_pos - exact pi_pos - exact zero_lt_two - apply (Set.mem_Icc.1 hx).1 - simp - apply mul_le_one - rw [div_le_one pi_pos] - exact two_le_pi - exact (Set.mem_Icc.1 hx).1 - exact (Set.mem_Icc.1 hx).2 - - have l₁ : 0 ≤ sin x := by - apply sin_nonneg_of_nonneg_of_le_pi (Set.mem_Icc.1 hx).1 - trans (1 : ℝ) - exact (Set.mem_Icc.1 hx).2 - trans π / 2 - exact one_le_pi_div_two - norm_num [pi_nonneg] - have l₂ : log (sin x) ≤ 0 := log_nonpos l₁ (sin_le_one x) - - simp only [norm_eq_abs, Function.comp_apply] - rw [abs_eq_neg_self.2 l₀] - rw [abs_eq_neg_self.2 l₂] - simp only [neg_le_neg_iff, ge_iff_le] - - have l₃ : x ∈ (Set.Ioi 0) := by - simp - exact lt_of_le_of_ne (Set.mem_Icc.1 hx).1 ( fun a => h'x (id (Eq.symm a)) ) - - have l₅ : 0 < (π / 2)⁻¹ * x := by - apply mul_pos - apply inv_pos.2 - apply div_pos pi_pos zero_lt_two - exact l₃ - - have : ∀ x ∈ (Set.Icc 0 (π / 2)), (π / 2)⁻¹ * x ≤ sin x := by - intro x hx - - have i₀ : 0 ∈ Set.Icc 0 π := - Set.left_mem_Icc.mpr pi_nonneg - have i₁ : π / 2 ∈ Set.Icc 0 π := - Set.mem_Icc.mpr ⟨div_nonneg pi_nonneg zero_le_two, half_le_self pi_nonneg⟩ - - have i₂ : 0 ≤ 1 - (π / 2)⁻¹ * x := by - rw [sub_nonneg] - calc (π / 2)⁻¹ * x - _ ≤ (π / 2)⁻¹ * (π / 2) := by - apply mul_le_mul_of_nonneg_left - exact (Set.mem_Icc.1 hx).2 - apply inv_nonneg.mpr (div_nonneg pi_nonneg zero_le_two) - _ = 1 := by - apply inv_mul_cancel - apply div_ne_zero_iff.mpr - constructor - · exact pi_ne_zero - · exact Ne.symm (NeZero.ne' 2) - - have i₃ : 0 ≤ (π / 2)⁻¹ * x := by - apply mul_nonneg - apply inv_nonneg.2 - apply div_nonneg - exact pi_nonneg - exact zero_le_two - exact (Set.mem_Icc.1 hx).1 - - have i₄ : 1 - (π / 2)⁻¹ * x + (π / 2)⁻¹ * x = 1 := by ring - - let B := strictConcaveOn_sin_Icc.concaveOn.2 i₀ i₁ i₂ i₃ i₄ - simp [Real.sin_pi_div_two] at B - rw [(by ring_nf; rw [mul_inv_cancel pi_ne_zero, one_mul] : 2 / π * x * (π / 2) = x)] at B - simpa - - apply log_le_log l₅ - apply this - apply Set.mem_Icc.mpr - constructor - · exact le_of_lt l₃ - · trans 1 - exact (Set.mem_Icc.1 hx).2 - exact one_le_pi_div_two - - -lemma intervalIntegrable_log_sin₁ : IntervalIntegrable (log ∘ sin) volume 0 1 := by - - have int_log : IntervalIntegrable (fun x ↦ ‖log x‖) volume 0 1 := by - apply IntervalIntegrable.norm - rw [← neg_neg log] - apply IntervalIntegrable.neg - apply intervalIntegrable_deriv_of_nonneg (g := fun x ↦ -(x * log x - x)) - · exact (continuous_mul_log.continuousOn.sub continuous_id.continuousOn).neg - · intro x hx - norm_num at hx - convert ((hasDerivAt_mul_log hx.left.ne.symm).sub (hasDerivAt_id x)).neg using 1 - norm_num - · intro x hx - norm_num at hx - rw [Pi.neg_apply, Left.nonneg_neg_iff] - exact (log_nonpos_iff hx.left).mpr hx.right.le - - - have int_log : IntervalIntegrable (fun x ↦ ‖log ((π / 2)⁻¹ * x)‖) volume 0 1 := by - - have A := IntervalIntegrable.comp_mul_right int_log (π / 2)⁻¹ - simp only [norm_eq_abs] at A - conv => - arg 1 - intro x - rw [mul_comm] - simp only [norm_eq_abs] - apply IntervalIntegrable.mono A - simp - trans Set.Icc 0 (π / 2) - exact Set.Icc_subset_Icc (Preorder.le_refl 0) one_le_pi_div_two - exact Set.Icc_subset_uIcc - exact Preorder.le_refl volume - - apply IntervalIntegrable.mono_fun' (g := fun x ↦ ‖log ((π / 2)⁻¹ * x)‖) - exact int_log - - -- AEStronglyMeasurable (log ∘ sin) (volume.restrict (Ι 0 1)) - apply ContinuousOn.aestronglyMeasurable - apply ContinuousOn.comp (t := Ι 0 1) - apply ContinuousOn.mono (s := {0}ᶜ) - exact continuousOn_log - intro x hx - by_contra contra - simp at contra - rw [contra, Set.left_mem_uIoc] at hx - linarith - exact continuousOn_sin - - -- Set.MapsTo sin (Ι 0 1) (Ι 0 1) - rw [Set.uIoc_of_le (zero_le_one' ℝ)] - exact fun x hx ↦ ⟨sin_pos_of_pos_of_le_one hx.1 hx.2, sin_le_one x⟩ - - -- MeasurableSet (Ι 0 1) - exact measurableSet_uIoc - - -- (fun x => ‖(log ∘ sin) x‖) ≤ᶠ[ae (volume.restrict (Ι 0 1))] ‖log‖ - dsimp [EventuallyLE] - rw [MeasureTheory.ae_restrict_iff] - apply MeasureTheory.ae_of_all - intro x hx - have : x ∈ Set.Icc 0 1 := by - simp - simp at hx - constructor - · exact le_of_lt hx.1 - · exact hx.2 - let A := logsinBound x this - simp only [Function.comp_apply, norm_eq_abs] at A - exact A - - apply measurableSet_le - apply Measurable.comp' - exact continuous_abs.measurable - exact Measurable.comp' measurable_log continuous_sin.measurable - -- Measurable fun a => |log ((π / 2)⁻¹ * a)| - apply Measurable.comp' - exact continuous_abs.measurable - apply Measurable.comp' - exact measurable_log - exact measurable_const_mul (π / 2)⁻¹ - -lemma intervalIntegrable_log_sin₂ : IntervalIntegrable (log ∘ sin) volume 0 (π / 2) := by - - apply IntervalIntegrable.trans (b := 1) - exact intervalIntegrable_log_sin₁ - - -- IntervalIntegrable (log ∘ sin) volume 1 (π / 2) - apply ContinuousOn.intervalIntegrable - apply ContinuousOn.comp continuousOn_log continuousOn_sin - intro x hx - rw [Set.uIcc_of_le, Set.mem_Icc] at hx - have : 0 < sin x := by - apply Real.sin_pos_of_pos_of_lt_pi - · calc 0 - _ < 1 := Real.zero_lt_one - _ ≤ x := hx.1 - · calc x - _ ≤ π / 2 := hx.2 - _ < π := div_two_lt_of_pos pi_pos - by_contra h₁x - simp at h₁x - rw [h₁x] at this - simp at this - exact one_le_pi_div_two - -lemma intervalIntegrable_log_sin : IntervalIntegrable (log ∘ sin) volume 0 π := by - apply IntervalIntegrable.trans (b := π / 2) - exact intervalIntegrable_log_sin₂ - let A := IntervalIntegrable.comp_sub_left intervalIntegrable_log_sin₂ π - simp at A - let B := IntervalIntegrable.symm A - have : π - π / 2 = π / 2 := by linarith - rwa [this] at B - -lemma intervalIntegrable_log_cos : IntervalIntegrable (log ∘ cos) volume 0 (π / 2) := by - let A := IntervalIntegrable.comp_sub_left intervalIntegrable_log_sin₂ (π / 2) - simp only [Function.comp_apply, sub_zero, sub_self] at A - simp_rw [sin_pi_div_two_sub] at A - have : (fun x => log (cos x)) = log ∘ cos := rfl - apply IntervalIntegrable.symm - rwa [← this] - - theorem logInt {t : ℝ} (ht : 0 < t) : @@ -281,108 +63,3 @@ theorem logInt exact (log_nonpos_iff hx.left).mpr hx.right.le · -- log is integrable on [[0, t]] simp [Set.mem_uIcc, ht] - - -lemma integral_log_sin : ∫ (x : ℝ) in (0)..(π / 2), log (sin x) = -log 2 * π/2 := by - - have t₀ {x : ℝ} : sin (2 * x) = 2 * sin x * cos x := sin_two_mul x - - have t₁ {x : ℝ} : log (sin (2 * x)) = log 2 + log (sin x) + log (cos x) := by - rw [sin_two_mul x, log_mul, log_mul] - exact Ne.symm (NeZero.ne' 2) - sorry - sorry - sorry - - have t₂ {x : ℝ} : log (sin x) = log (sin (2 * x)) - log 2 - log (cos x) := by - rw [t₁] - ring - - conv => - left - arg 1 - intro x - rw [t₂] - - rw [intervalIntegral.integral_sub, intervalIntegral.integral_sub] - rw [intervalIntegral.integral_const] - rw [intervalIntegral.integral_comp_mul_left (c := 2) (f := fun x ↦ log (sin x))] - simp - have : 2 * (π / 2) = π := by linarith - rw [this] - - have : ∫ (x : ℝ) in (0)..π, log (sin x) = 2 * ∫ (x : ℝ) in (0)..(π / 2), log (sin x) := by - sorry - rw [this] - have : ∫ (x : ℝ) in (0)..(π / 2), log (sin x) = ∫ (x : ℝ) in (0)..(π / 2), log (cos x) := by - sorry - rw [← this] - simp - linarith - - exact Ne.symm (NeZero.ne' 2) - -- IntervalIntegrable (fun x => log (sin (2 * x))) volume 0 (π / 2) - sorry - -- IntervalIntegrable (fun x => log 2) volume 0 (π / 2) - simp - -- IntervalIntegrable (fun x => log (sin (2 * x)) - log 2) volume 0 (π / 2) - apply IntervalIntegrable.sub - -- -- IntervalIntegrable (fun x => log (sin (2 * x))) volume 0 (π / 2) - sorry - -- -- IntervalIntegrable (fun x => log 2) volume 0 (π / 2) - simp - -- -- IntervalIntegrable (fun x => log (cos x)) volume 0 (π / 2) - exact intervalIntegrable_log_cos - - -lemma int₁₁ : ∫ (x : ℝ) in (0)..π, log (4 * sin x ^ 2) = 0 := by - sorry - - -lemma int₁ : - ∫ x in (0)..(2 * π), log ‖circleMap 0 1 x - 1‖ = 0 := by - - have {x : ℝ} : log ‖circleMap 0 1 x - 1‖ = log (4 * sin (x / 2) ^ 2) / 2 := by - dsimp [Complex.abs] - rw [log_sqrt (Complex.normSq_nonneg (circleMap 0 1 x - 1))] - congr - calc Complex.normSq (circleMap 0 1 x - 1) - _ = (cos x - 1) * (cos x - 1) + sin x * sin x := by - dsimp [circleMap] - rw [Complex.normSq_apply] - simp - _ = sin x ^ 2 + cos x ^ 2 + 1 - 2 * cos x := by - ring - _ = 2 - 2 * cos x := by - rw [sin_sq_add_cos_sq] - norm_num - _ = 2 - 2 * cos (2 * (x / 2)) := by - rw [← mul_div_assoc] - congr; norm_num - _ = 4 - 4 * Real.cos (x / 2) ^ 2 := by - rw [cos_two_mul] - ring - _ = 4 * sin (x / 2) ^ 2 := by - nth_rw 1 [← mul_one 4, ← sin_sq_add_cos_sq (x / 2)] - ring - simp_rw [this] - simp - - have : ∫ (x : ℝ) in (0)..2 * π, log (4 * sin (x / 2) ^ 2) = 2 * ∫ (x : ℝ) in (0)..π, log (4 * sin x ^ 2) := by - have : 1 = 2 * (2 : ℝ)⁻¹ := by exact Eq.symm (mul_inv_cancel_of_invertible 2) - nth_rw 1 [← one_mul (∫ (x : ℝ) in (0)..2 * π, log (4 * sin (x / 2) ^ 2))] - rw [← mul_inv_cancel_of_invertible 2, mul_assoc] - let f := fun y ↦ log (4 * sin y ^ 2) - have {x : ℝ} : log (4 * sin (x / 2) ^ 2) = f (x / 2) := by simp - conv => - left - right - right - arg 1 - intro x - rw [this] - rw [intervalIntegral.inv_mul_integral_comp_div 2] - simp - rw [this] - simp - exact int₁₁ diff --git a/Nevanlinna/specialFunctions_Integral_log_sin.lean b/Nevanlinna/specialFunctions_Integral_log_sin.lean index 92dcdc4..e4423a3 100644 --- a/Nevanlinna/specialFunctions_Integral_log_sin.lean +++ b/Nevanlinna/specialFunctions_Integral_log_sin.lean @@ -6,7 +6,6 @@ import Mathlib.MeasureTheory.Measure.Restrict open scoped Interval Topology open Real Filter MeasureTheory intervalIntegral --- The following theorem was suggested by Gareth Ma on Zulip lemma logsinBound : ∀ x ∈ (Set.Icc 0 1), ‖(log ∘ sin) x‖ ≤ ‖log ((π / 2)⁻¹ * x)‖ := by @@ -227,62 +226,6 @@ lemma intervalIntegrable_log_cos : IntervalIntegrable (log ∘ cos) volume 0 (π rwa [← this] -theorem logInt - {t : ℝ} - (ht : 0 < t) : - ∫ x in (0 : ℝ)..t, log x = t * log t - t := by - rw [← integral_add_adjacent_intervals (b := 1)] - trans (-1) + (t * log t - t + 1) - · congr - · -- ∫ x in 0..1, log x = -1, same proof as before - rw [integral_eq_sub_of_hasDerivAt_of_tendsto (f := fun x ↦ x * log x - x) (fa := 0) (fb := -1)] - · simp - · simp - · intro x hx - norm_num at hx - convert (hasDerivAt_mul_log hx.left.ne.symm).sub (hasDerivAt_id x) using 1 - norm_num - · rw [← neg_neg log] - apply IntervalIntegrable.neg - apply intervalIntegrable_deriv_of_nonneg (g := fun x ↦ -(x * log x - x)) - · exact (continuous_mul_log.continuousOn.sub continuous_id.continuousOn).neg - · intro x hx - norm_num at hx - convert ((hasDerivAt_mul_log hx.left.ne.symm).sub (hasDerivAt_id x)).neg using 1 - norm_num - · intro x hx - norm_num at hx - rw [Pi.neg_apply, Left.nonneg_neg_iff] - exact (log_nonpos_iff hx.left).mpr hx.right.le - · have := tendsto_log_mul_rpow_nhds_zero zero_lt_one - simp_rw [rpow_one, mul_comm] at this - -- tendsto_nhdsWithin_of_tendsto_nhds should be under Tendsto namespace - convert this.sub (tendsto_nhdsWithin_of_tendsto_nhds tendsto_id) - norm_num - · rw [(by simp : -1 = 1 * log 1 - 1)] - apply tendsto_nhdsWithin_of_tendsto_nhds - exact (continuousAt_id.mul (continuousAt_log one_ne_zero)).sub continuousAt_id - · -- ∫ x in 1..t, log x = t * log t + 1, just use integral_log_of_pos - rw [integral_log_of_pos zero_lt_one ht] - norm_num - · abel - · -- log is integrable on [[0, 1]] - rw [← neg_neg log] - apply IntervalIntegrable.neg - apply intervalIntegrable_deriv_of_nonneg (g := fun x ↦ -(x * log x - x)) - · exact (continuous_mul_log.continuousOn.sub continuous_id.continuousOn).neg - · intro x hx - norm_num at hx - convert ((hasDerivAt_mul_log hx.left.ne.symm).sub (hasDerivAt_id x)).neg using 1 - norm_num - · intro x hx - norm_num at hx - rw [Pi.neg_apply, Left.nonneg_neg_iff] - exact (log_nonpos_iff hx.left).mpr hx.right.le - · -- log is integrable on [[0, t]] - simp [Set.mem_uIcc, ht] - - lemma integral_log_sin : ∫ (x : ℝ) in (0)..(π / 2), log (sin x) = -log 2 * π/2 := by have t₀ {x : ℝ} : sin (2 * x) = 2 * sin x * cos x := sin_two_mul x @@ -333,56 +276,3 @@ lemma integral_log_sin : ∫ (x : ℝ) in (0)..(π / 2), log (sin x) = -log 2 * simp -- -- IntervalIntegrable (fun x => log (cos x)) volume 0 (π / 2) exact intervalIntegrable_log_cos - - -lemma int₁₁ : ∫ (x : ℝ) in (0)..π, log (4 * sin x ^ 2) = 0 := by - sorry - - -lemma int₁ : - ∫ x in (0)..(2 * π), log ‖circleMap 0 1 x - 1‖ = 0 := by - - have {x : ℝ} : log ‖circleMap 0 1 x - 1‖ = log (4 * sin (x / 2) ^ 2) / 2 := by - dsimp [Complex.abs] - rw [log_sqrt (Complex.normSq_nonneg (circleMap 0 1 x - 1))] - congr - calc Complex.normSq (circleMap 0 1 x - 1) - _ = (cos x - 1) * (cos x - 1) + sin x * sin x := by - dsimp [circleMap] - rw [Complex.normSq_apply] - simp - _ = sin x ^ 2 + cos x ^ 2 + 1 - 2 * cos x := by - ring - _ = 2 - 2 * cos x := by - rw [sin_sq_add_cos_sq] - norm_num - _ = 2 - 2 * cos (2 * (x / 2)) := by - rw [← mul_div_assoc] - congr; norm_num - _ = 4 - 4 * Real.cos (x / 2) ^ 2 := by - rw [cos_two_mul] - ring - _ = 4 * sin (x / 2) ^ 2 := by - nth_rw 1 [← mul_one 4, ← sin_sq_add_cos_sq (x / 2)] - ring - simp_rw [this] - simp - - have : ∫ (x : ℝ) in (0)..2 * π, log (4 * sin (x / 2) ^ 2) = 2 * ∫ (x : ℝ) in (0)..π, log (4 * sin x ^ 2) := by - have : 1 = 2 * (2 : ℝ)⁻¹ := by exact Eq.symm (mul_inv_cancel_of_invertible 2) - nth_rw 1 [← one_mul (∫ (x : ℝ) in (0)..2 * π, log (4 * sin (x / 2) ^ 2))] - rw [← mul_inv_cancel_of_invertible 2, mul_assoc] - let f := fun y ↦ log (4 * sin y ^ 2) - have {x : ℝ} : log (4 * sin (x / 2) ^ 2) = f (x / 2) := by simp - conv => - left - right - right - arg 1 - intro x - rw [this] - rw [intervalIntegral.inv_mul_integral_comp_div 2] - simp - rw [this] - simp - exact int₁₁ diff --git a/Nevanlinna/specialFunctions_Integrals.lean b/Nevanlinna/specialFunctions_Integrals.lean deleted file mode 100644 index 92dcdc4..0000000 --- a/Nevanlinna/specialFunctions_Integrals.lean +++ /dev/null @@ -1,388 +0,0 @@ -import Mathlib.Analysis.SpecialFunctions.Integrals -import Mathlib.Analysis.SpecialFunctions.Log.NegMulLog -import Mathlib.MeasureTheory.Integral.CircleIntegral -import Mathlib.MeasureTheory.Measure.Restrict - -open scoped Interval Topology -open Real Filter MeasureTheory intervalIntegral - --- The following theorem was suggested by Gareth Ma on Zulip - - -lemma logsinBound : ∀ x ∈ (Set.Icc 0 1), ‖(log ∘ sin) x‖ ≤ ‖log ((π / 2)⁻¹ * x)‖ := by - - intro x hx - by_cases h'x : x = 0 - · rw [h'x]; simp - - -- Now handle the case where x ≠ 0 - have l₀ : log ((π / 2)⁻¹ * x) ≤ 0 := by - apply log_nonpos - apply mul_nonneg - apply le_of_lt - apply inv_pos.2 - apply div_pos - exact pi_pos - exact zero_lt_two - apply (Set.mem_Icc.1 hx).1 - simp - apply mul_le_one - rw [div_le_one pi_pos] - exact two_le_pi - exact (Set.mem_Icc.1 hx).1 - exact (Set.mem_Icc.1 hx).2 - - have l₁ : 0 ≤ sin x := by - apply sin_nonneg_of_nonneg_of_le_pi (Set.mem_Icc.1 hx).1 - trans (1 : ℝ) - exact (Set.mem_Icc.1 hx).2 - trans π / 2 - exact one_le_pi_div_two - norm_num [pi_nonneg] - have l₂ : log (sin x) ≤ 0 := log_nonpos l₁ (sin_le_one x) - - simp only [norm_eq_abs, Function.comp_apply] - rw [abs_eq_neg_self.2 l₀] - rw [abs_eq_neg_self.2 l₂] - simp only [neg_le_neg_iff, ge_iff_le] - - have l₃ : x ∈ (Set.Ioi 0) := by - simp - exact lt_of_le_of_ne (Set.mem_Icc.1 hx).1 ( fun a => h'x (id (Eq.symm a)) ) - - have l₅ : 0 < (π / 2)⁻¹ * x := by - apply mul_pos - apply inv_pos.2 - apply div_pos pi_pos zero_lt_two - exact l₃ - - have : ∀ x ∈ (Set.Icc 0 (π / 2)), (π / 2)⁻¹ * x ≤ sin x := by - intro x hx - - have i₀ : 0 ∈ Set.Icc 0 π := - Set.left_mem_Icc.mpr pi_nonneg - have i₁ : π / 2 ∈ Set.Icc 0 π := - Set.mem_Icc.mpr ⟨div_nonneg pi_nonneg zero_le_two, half_le_self pi_nonneg⟩ - - have i₂ : 0 ≤ 1 - (π / 2)⁻¹ * x := by - rw [sub_nonneg] - calc (π / 2)⁻¹ * x - _ ≤ (π / 2)⁻¹ * (π / 2) := by - apply mul_le_mul_of_nonneg_left - exact (Set.mem_Icc.1 hx).2 - apply inv_nonneg.mpr (div_nonneg pi_nonneg zero_le_two) - _ = 1 := by - apply inv_mul_cancel - apply div_ne_zero_iff.mpr - constructor - · exact pi_ne_zero - · exact Ne.symm (NeZero.ne' 2) - - have i₃ : 0 ≤ (π / 2)⁻¹ * x := by - apply mul_nonneg - apply inv_nonneg.2 - apply div_nonneg - exact pi_nonneg - exact zero_le_two - exact (Set.mem_Icc.1 hx).1 - - have i₄ : 1 - (π / 2)⁻¹ * x + (π / 2)⁻¹ * x = 1 := by ring - - let B := strictConcaveOn_sin_Icc.concaveOn.2 i₀ i₁ i₂ i₃ i₄ - simp [Real.sin_pi_div_two] at B - rw [(by ring_nf; rw [mul_inv_cancel pi_ne_zero, one_mul] : 2 / π * x * (π / 2) = x)] at B - simpa - - apply log_le_log l₅ - apply this - apply Set.mem_Icc.mpr - constructor - · exact le_of_lt l₃ - · trans 1 - exact (Set.mem_Icc.1 hx).2 - exact one_le_pi_div_two - - -lemma intervalIntegrable_log_sin₁ : IntervalIntegrable (log ∘ sin) volume 0 1 := by - - have int_log : IntervalIntegrable (fun x ↦ ‖log x‖) volume 0 1 := by - apply IntervalIntegrable.norm - rw [← neg_neg log] - apply IntervalIntegrable.neg - apply intervalIntegrable_deriv_of_nonneg (g := fun x ↦ -(x * log x - x)) - · exact (continuous_mul_log.continuousOn.sub continuous_id.continuousOn).neg - · intro x hx - norm_num at hx - convert ((hasDerivAt_mul_log hx.left.ne.symm).sub (hasDerivAt_id x)).neg using 1 - norm_num - · intro x hx - norm_num at hx - rw [Pi.neg_apply, Left.nonneg_neg_iff] - exact (log_nonpos_iff hx.left).mpr hx.right.le - - - have int_log : IntervalIntegrable (fun x ↦ ‖log ((π / 2)⁻¹ * x)‖) volume 0 1 := by - - have A := IntervalIntegrable.comp_mul_right int_log (π / 2)⁻¹ - simp only [norm_eq_abs] at A - conv => - arg 1 - intro x - rw [mul_comm] - simp only [norm_eq_abs] - apply IntervalIntegrable.mono A - simp - trans Set.Icc 0 (π / 2) - exact Set.Icc_subset_Icc (Preorder.le_refl 0) one_le_pi_div_two - exact Set.Icc_subset_uIcc - exact Preorder.le_refl volume - - apply IntervalIntegrable.mono_fun' (g := fun x ↦ ‖log ((π / 2)⁻¹ * x)‖) - exact int_log - - -- AEStronglyMeasurable (log ∘ sin) (volume.restrict (Ι 0 1)) - apply ContinuousOn.aestronglyMeasurable - apply ContinuousOn.comp (t := Ι 0 1) - apply ContinuousOn.mono (s := {0}ᶜ) - exact continuousOn_log - intro x hx - by_contra contra - simp at contra - rw [contra, Set.left_mem_uIoc] at hx - linarith - exact continuousOn_sin - - -- Set.MapsTo sin (Ι 0 1) (Ι 0 1) - rw [Set.uIoc_of_le (zero_le_one' ℝ)] - exact fun x hx ↦ ⟨sin_pos_of_pos_of_le_one hx.1 hx.2, sin_le_one x⟩ - - -- MeasurableSet (Ι 0 1) - exact measurableSet_uIoc - - -- (fun x => ‖(log ∘ sin) x‖) ≤ᶠ[ae (volume.restrict (Ι 0 1))] ‖log‖ - dsimp [EventuallyLE] - rw [MeasureTheory.ae_restrict_iff] - apply MeasureTheory.ae_of_all - intro x hx - have : x ∈ Set.Icc 0 1 := by - simp - simp at hx - constructor - · exact le_of_lt hx.1 - · exact hx.2 - let A := logsinBound x this - simp only [Function.comp_apply, norm_eq_abs] at A - exact A - - apply measurableSet_le - apply Measurable.comp' - exact continuous_abs.measurable - exact Measurable.comp' measurable_log continuous_sin.measurable - -- Measurable fun a => |log ((π / 2)⁻¹ * a)| - apply Measurable.comp' - exact continuous_abs.measurable - apply Measurable.comp' - exact measurable_log - exact measurable_const_mul (π / 2)⁻¹ - -lemma intervalIntegrable_log_sin₂ : IntervalIntegrable (log ∘ sin) volume 0 (π / 2) := by - - apply IntervalIntegrable.trans (b := 1) - exact intervalIntegrable_log_sin₁ - - -- IntervalIntegrable (log ∘ sin) volume 1 (π / 2) - apply ContinuousOn.intervalIntegrable - apply ContinuousOn.comp continuousOn_log continuousOn_sin - intro x hx - rw [Set.uIcc_of_le, Set.mem_Icc] at hx - have : 0 < sin x := by - apply Real.sin_pos_of_pos_of_lt_pi - · calc 0 - _ < 1 := Real.zero_lt_one - _ ≤ x := hx.1 - · calc x - _ ≤ π / 2 := hx.2 - _ < π := div_two_lt_of_pos pi_pos - by_contra h₁x - simp at h₁x - rw [h₁x] at this - simp at this - exact one_le_pi_div_two - -lemma intervalIntegrable_log_sin : IntervalIntegrable (log ∘ sin) volume 0 π := by - apply IntervalIntegrable.trans (b := π / 2) - exact intervalIntegrable_log_sin₂ - let A := IntervalIntegrable.comp_sub_left intervalIntegrable_log_sin₂ π - simp at A - let B := IntervalIntegrable.symm A - have : π - π / 2 = π / 2 := by linarith - rwa [this] at B - -lemma intervalIntegrable_log_cos : IntervalIntegrable (log ∘ cos) volume 0 (π / 2) := by - let A := IntervalIntegrable.comp_sub_left intervalIntegrable_log_sin₂ (π / 2) - simp only [Function.comp_apply, sub_zero, sub_self] at A - simp_rw [sin_pi_div_two_sub] at A - have : (fun x => log (cos x)) = log ∘ cos := rfl - apply IntervalIntegrable.symm - rwa [← this] - - -theorem logInt - {t : ℝ} - (ht : 0 < t) : - ∫ x in (0 : ℝ)..t, log x = t * log t - t := by - rw [← integral_add_adjacent_intervals (b := 1)] - trans (-1) + (t * log t - t + 1) - · congr - · -- ∫ x in 0..1, log x = -1, same proof as before - rw [integral_eq_sub_of_hasDerivAt_of_tendsto (f := fun x ↦ x * log x - x) (fa := 0) (fb := -1)] - · simp - · simp - · intro x hx - norm_num at hx - convert (hasDerivAt_mul_log hx.left.ne.symm).sub (hasDerivAt_id x) using 1 - norm_num - · rw [← neg_neg log] - apply IntervalIntegrable.neg - apply intervalIntegrable_deriv_of_nonneg (g := fun x ↦ -(x * log x - x)) - · exact (continuous_mul_log.continuousOn.sub continuous_id.continuousOn).neg - · intro x hx - norm_num at hx - convert ((hasDerivAt_mul_log hx.left.ne.symm).sub (hasDerivAt_id x)).neg using 1 - norm_num - · intro x hx - norm_num at hx - rw [Pi.neg_apply, Left.nonneg_neg_iff] - exact (log_nonpos_iff hx.left).mpr hx.right.le - · have := tendsto_log_mul_rpow_nhds_zero zero_lt_one - simp_rw [rpow_one, mul_comm] at this - -- tendsto_nhdsWithin_of_tendsto_nhds should be under Tendsto namespace - convert this.sub (tendsto_nhdsWithin_of_tendsto_nhds tendsto_id) - norm_num - · rw [(by simp : -1 = 1 * log 1 - 1)] - apply tendsto_nhdsWithin_of_tendsto_nhds - exact (continuousAt_id.mul (continuousAt_log one_ne_zero)).sub continuousAt_id - · -- ∫ x in 1..t, log x = t * log t + 1, just use integral_log_of_pos - rw [integral_log_of_pos zero_lt_one ht] - norm_num - · abel - · -- log is integrable on [[0, 1]] - rw [← neg_neg log] - apply IntervalIntegrable.neg - apply intervalIntegrable_deriv_of_nonneg (g := fun x ↦ -(x * log x - x)) - · exact (continuous_mul_log.continuousOn.sub continuous_id.continuousOn).neg - · intro x hx - norm_num at hx - convert ((hasDerivAt_mul_log hx.left.ne.symm).sub (hasDerivAt_id x)).neg using 1 - norm_num - · intro x hx - norm_num at hx - rw [Pi.neg_apply, Left.nonneg_neg_iff] - exact (log_nonpos_iff hx.left).mpr hx.right.le - · -- log is integrable on [[0, t]] - simp [Set.mem_uIcc, ht] - - -lemma integral_log_sin : ∫ (x : ℝ) in (0)..(π / 2), log (sin x) = -log 2 * π/2 := by - - have t₀ {x : ℝ} : sin (2 * x) = 2 * sin x * cos x := sin_two_mul x - - have t₁ {x : ℝ} : log (sin (2 * x)) = log 2 + log (sin x) + log (cos x) := by - rw [sin_two_mul x, log_mul, log_mul] - exact Ne.symm (NeZero.ne' 2) - sorry - sorry - sorry - - have t₂ {x : ℝ} : log (sin x) = log (sin (2 * x)) - log 2 - log (cos x) := by - rw [t₁] - ring - - conv => - left - arg 1 - intro x - rw [t₂] - - rw [intervalIntegral.integral_sub, intervalIntegral.integral_sub] - rw [intervalIntegral.integral_const] - rw [intervalIntegral.integral_comp_mul_left (c := 2) (f := fun x ↦ log (sin x))] - simp - have : 2 * (π / 2) = π := by linarith - rw [this] - - have : ∫ (x : ℝ) in (0)..π, log (sin x) = 2 * ∫ (x : ℝ) in (0)..(π / 2), log (sin x) := by - sorry - rw [this] - have : ∫ (x : ℝ) in (0)..(π / 2), log (sin x) = ∫ (x : ℝ) in (0)..(π / 2), log (cos x) := by - sorry - rw [← this] - simp - linarith - - exact Ne.symm (NeZero.ne' 2) - -- IntervalIntegrable (fun x => log (sin (2 * x))) volume 0 (π / 2) - sorry - -- IntervalIntegrable (fun x => log 2) volume 0 (π / 2) - simp - -- IntervalIntegrable (fun x => log (sin (2 * x)) - log 2) volume 0 (π / 2) - apply IntervalIntegrable.sub - -- -- IntervalIntegrable (fun x => log (sin (2 * x))) volume 0 (π / 2) - sorry - -- -- IntervalIntegrable (fun x => log 2) volume 0 (π / 2) - simp - -- -- IntervalIntegrable (fun x => log (cos x)) volume 0 (π / 2) - exact intervalIntegrable_log_cos - - -lemma int₁₁ : ∫ (x : ℝ) in (0)..π, log (4 * sin x ^ 2) = 0 := by - sorry - - -lemma int₁ : - ∫ x in (0)..(2 * π), log ‖circleMap 0 1 x - 1‖ = 0 := by - - have {x : ℝ} : log ‖circleMap 0 1 x - 1‖ = log (4 * sin (x / 2) ^ 2) / 2 := by - dsimp [Complex.abs] - rw [log_sqrt (Complex.normSq_nonneg (circleMap 0 1 x - 1))] - congr - calc Complex.normSq (circleMap 0 1 x - 1) - _ = (cos x - 1) * (cos x - 1) + sin x * sin x := by - dsimp [circleMap] - rw [Complex.normSq_apply] - simp - _ = sin x ^ 2 + cos x ^ 2 + 1 - 2 * cos x := by - ring - _ = 2 - 2 * cos x := by - rw [sin_sq_add_cos_sq] - norm_num - _ = 2 - 2 * cos (2 * (x / 2)) := by - rw [← mul_div_assoc] - congr; norm_num - _ = 4 - 4 * Real.cos (x / 2) ^ 2 := by - rw [cos_two_mul] - ring - _ = 4 * sin (x / 2) ^ 2 := by - nth_rw 1 [← mul_one 4, ← sin_sq_add_cos_sq (x / 2)] - ring - simp_rw [this] - simp - - have : ∫ (x : ℝ) in (0)..2 * π, log (4 * sin (x / 2) ^ 2) = 2 * ∫ (x : ℝ) in (0)..π, log (4 * sin x ^ 2) := by - have : 1 = 2 * (2 : ℝ)⁻¹ := by exact Eq.symm (mul_inv_cancel_of_invertible 2) - nth_rw 1 [← one_mul (∫ (x : ℝ) in (0)..2 * π, log (4 * sin (x / 2) ^ 2))] - rw [← mul_inv_cancel_of_invertible 2, mul_assoc] - let f := fun y ↦ log (4 * sin y ^ 2) - have {x : ℝ} : log (4 * sin (x / 2) ^ 2) = f (x / 2) := by simp - conv => - left - right - right - arg 1 - intro x - rw [this] - rw [intervalIntegral.inv_mul_integral_comp_div 2] - simp - rw [this] - simp - exact int₁₁