Theorem: le_radius_cauchyPowerSeries
File: Mathlib/MeasureTheory/Integral/CircleIntegral.lean

tactic: refine'
  (cauchyPowerSeries f c R).le_radius_of_bound
    ((2 * π)⁻¹ * ∫ θ : ℝ in (0)..2 * π, ‖f (circleMap c R θ)‖) fun n => _
state_before: E : Type u_1
inst✝² : NormedAddCommGroup E
inst✝¹ : NormedSpace ℂ E
inst✝ : CompleteSpace E
f : ℂ → E
c : ℂ
R : ℝ≥0
⊢ ↑R ≤ FormalMultilinearSeries.radius (cauchyPowerSeries f c ↑R)

tactic: refine' (mul_le_mul_of_nonneg_right (norm_cauchyPowerSeries_le _ _ _ _)
  (pow_nonneg R.coe_nonneg _)).trans _
state_before: E : Type u_1
inst✝² : NormedAddCommGroup E
inst✝¹ : NormedSpace ℂ E
inst✝ : CompleteSpace E
f : ℂ → E
c : ℂ
R : ℝ≥0
n : ℕ
⊢ ‖cauchyPowerSeries f c (↑R) n‖ * ↑R ^ n ≤ (2 * π)⁻¹ * ∫ (θ : ℝ) in 0 ..2 * π, ‖f (circleMap c (↑R) θ)‖

tactic: rw [_root_.abs_of_nonneg R.coe_nonneg]
state_before: E : Type u_1
inst✝² : NormedAddCommGroup E
inst✝¹ : NormedSpace ℂ E
inst✝ : CompleteSpace E
f : ℂ → E
c : ℂ
R : ℝ≥0
n : ℕ
⊢ ((2 * π)⁻¹ * ∫ (θ : ℝ) in 0 ..2 * π, ‖f (circleMap c (↑R) θ)‖) * (Abs.abs ↑R)⁻¹ ^ n * ↑R ^ n ≤
    (2 * π)⁻¹ * ∫ (θ : ℝ) in 0 ..2 * π, ‖f (circleMap c (↑R) θ)‖

tactic: cases' eq_or_ne (R ^ n : ℝ) 0 with hR hR
state_before: E : Type u_1
inst✝² : NormedAddCommGroup E
inst✝¹ : NormedSpace ℂ E
inst✝ : CompleteSpace E
f : ℂ → E
c : ℂ
R : ℝ≥0
n : ℕ
⊢ ((2 * π)⁻¹ * ∫ (θ : ℝ) in 0 ..2 * π, ‖f (circleMap c (↑R) θ)‖) * (↑R)⁻¹ ^ n * ↑R ^ n ≤
    (2 * π)⁻¹ * ∫ (θ : ℝ) in 0 ..2 * π, ‖f (circleMap c (↑R) θ)‖

tactic: rw_mod_cast [hR, mul_zero]
state_before: case inl
E : Type u_1
inst✝² : NormedAddCommGroup E
inst✝¹ : NormedSpace ℂ E
inst✝ : CompleteSpace E
f : ℂ → E
c : ℂ
R : ℝ≥0
n : ℕ
hR : ↑(R ^ n) = 0
⊢ ((2 * π)⁻¹ * ∫ (θ : ℝ) in 0 ..2 * π, ‖f (circleMap c (↑R) θ)‖) * (↑R)⁻¹ ^ n * ↑R ^ n ≤
    (2 * π)⁻¹ * ∫ (θ : ℝ) in 0 ..2 * π, ‖f (circleMap c (↑R) θ)‖

tactic: exact mul_nonneg (inv_nonneg.2 Real.two_pi_pos.le)
  (intervalIntegral.integral_nonneg Real.two_pi_pos.le fun _ _ => norm_nonneg _)
state_before: case inl
E : Type u_1
inst✝² : NormedAddCommGroup E
inst✝¹ : NormedSpace ℂ E
inst✝ : CompleteSpace E
f : ℂ → E
c : ℂ
R : ℝ≥0
n : ℕ
hR : R ^ n = 0
⊢ 0 ≤ (2 * π)⁻¹ * ∫ (θ : ℝ) in 0 ..2 * π, ‖f (circleMap c (↑R) θ)‖

tactic: rw [inv_pow]
state_before: case inr
E : Type u_1
inst✝² : NormedAddCommGroup E
inst✝¹ : NormedSpace ℂ E
inst✝ : CompleteSpace E
f : ℂ → E
c : ℂ
R : ℝ≥0
n : ℕ
hR : ↑(R ^ n) ≠ 0
⊢ ((2 * π)⁻¹ * ∫ (θ : ℝ) in 0 ..2 * π, ‖f (circleMap c (↑R) θ)‖) * (↑R)⁻¹ ^ n * ↑R ^ n ≤
    (2 * π)⁻¹ * ∫ (θ : ℝ) in 0 ..2 * π, ‖f (circleMap c (↑R) θ)‖

tactic: have : (R:ℝ) ^ n ≠ 0 := by norm_cast at hR ⊢
state_before: case inr
E : Type u_1
inst✝² : NormedAddCommGroup E
inst✝¹ : NormedSpace ℂ E
inst✝ : CompleteSpace E
f : ℂ → E
c : ℂ
R : ℝ≥0
n : ℕ
hR : ↑(R ^ n) ≠ 0
⊢ ((2 * π)⁻¹ * ∫ (θ : ℝ) in 0 ..2 * π, ‖f (circleMap c (↑R) θ)‖) * (↑R ^ n)⁻¹ * ↑R ^ n ≤
    (2 * π)⁻¹ * ∫ (θ : ℝ) in 0 ..2 * π, ‖f (circleMap c (↑R) θ)‖

tactic: rw [inv_mul_cancel_right₀ this]
state_before: case inr
E : Type u_1
inst✝² : NormedAddCommGroup E
inst✝¹ : NormedSpace ℂ E
inst✝ : CompleteSpace E
f : ℂ → E
c : ℂ
R : ℝ≥0
n : ℕ
hR : ↑(R ^ n) ≠ 0
this : ↑R ^ n ≠ 0
⊢ ((2 * π)⁻¹ * ∫ (θ : ℝ) in 0 ..2 * π, ‖f (circleMap c (↑R) θ)‖) * (↑R ^ n)⁻¹ * ↑R ^ n ≤
    (2 * π)⁻¹ * ∫ (θ : ℝ) in 0 ..2 * π, ‖f (circleMap c (↑R) θ)‖

tactic: norm_cast at hR ⊢
state_before: E : Type u_1
inst✝² : NormedAddCommGroup E
inst✝¹ : NormedSpace ℂ E
inst✝ : CompleteSpace E
f : ℂ → E
c : ℂ
R : ℝ≥0
n : ℕ
hR : ↑(R ^ n) ≠ 0
⊢ ↑R ^ n ≠ 0