diff --git a/Nevanlinna/specialFunctions_Integrals.lean b/Nevanlinna/specialFunctions_Integrals.lean index 0ceb7da..657d37a 100644 --- a/Nevanlinna/specialFunctions_Integrals.lean +++ b/Nevanlinna/specialFunctions_Integrals.lean @@ -66,9 +66,10 @@ theorem logInt lemma int₁ : ∫ x in (0)..(2 * π), log ‖circleMap 0 1 x - 1‖ = 0 := by - - - have {x : ℝ} : Complex.normSq (circleMap 0 1 x - 1) = 2 - 2 * cos x := 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] @@ -79,35 +80,35 @@ lemma int₁ : _ = 2 - 2 * cos x := by rw [sin_sq_add_cos_sq] norm_num - - - have {x : ℝ} : 2 - 2 * cos x = 4 * sin (x / 2) ^ 2 := by - calc 2 - 2 * cos x _ = 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] - norm_num + ring _ = 4 * sin (x / 2) ^ 2 := by - nth_rw 1 [← mul_one 4] - nth_rw 1 [← sin_sq_add_cos_sq (x / 2)] - rw [mul_add] - abel - - - - - - - dsimp [Complex.abs] - sorry - - - - - sorry + 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