Proof of Theorem fourier2
| Step | Hyp | Ref | Expression | 
|---|
| 1 |  | fourier2.f | . . . . . 6
⊢ (𝜑 → 𝐹:ℝ⟶ℝ) | 
| 2 |  | fourier2.t | . . . . . 6
⊢ 𝑇 = (2 ·
π) | 
| 3 |  | fourier2.per | . . . . . 6
⊢ ((𝜑 ∧ 𝑥 ∈ ℝ) → (𝐹‘(𝑥 + 𝑇)) = (𝐹‘𝑥)) | 
| 4 |  | fourier2.g | . . . . . 6
⊢ 𝐺 = ((ℝ D 𝐹) ↾ (-π(,)π)) | 
| 5 |  | fourier2.dmdv | . . . . . 6
⊢ (𝜑 → ((-π(,)π) ∖
dom 𝐺) ∈
Fin) | 
| 6 |  | fourier2.dvcn | . . . . . 6
⊢ (𝜑 → 𝐺 ∈ (dom 𝐺–cn→ℂ)) | 
| 7 |  | fourier2.rlim | . . . . . 6
⊢ ((𝜑 ∧ 𝑥 ∈ ((-π[,)π) ∖ dom 𝐺)) → ((𝐺 ↾ (𝑥(,)+∞)) limℂ 𝑥) ≠ ∅) | 
| 8 |  | fourier2.llim | . . . . . 6
⊢ ((𝜑 ∧ 𝑥 ∈ ((-π(,]π) ∖ dom 𝐺)) → ((𝐺 ↾ (-∞(,)𝑥)) limℂ 𝑥) ≠ ∅) | 
| 9 |  | fourier2.x | . . . . . 6
⊢ (𝜑 → 𝑋 ∈ ℝ) | 
| 10 | 1, 2, 3, 4, 5, 6, 7, 8, 9 | fourierdlem106 46227 | . . . . 5
⊢ (𝜑 → (((𝐹 ↾ (-∞(,)𝑋)) limℂ 𝑋) ≠ ∅ ∧ ((𝐹 ↾ (𝑋(,)+∞)) limℂ 𝑋) ≠
∅)) | 
| 11 | 10 | simpld 494 | . . . 4
⊢ (𝜑 → ((𝐹 ↾ (-∞(,)𝑋)) limℂ 𝑋) ≠ ∅) | 
| 12 |  | n0 4353 | . . . 4
⊢ (((𝐹 ↾ (-∞(,)𝑋)) limℂ 𝑋) ≠ ∅ ↔
∃𝑙 𝑙 ∈ ((𝐹 ↾ (-∞(,)𝑋)) limℂ 𝑋)) | 
| 13 | 11, 12 | sylib 218 | . . 3
⊢ (𝜑 → ∃𝑙 𝑙 ∈ ((𝐹 ↾ (-∞(,)𝑋)) limℂ 𝑋)) | 
| 14 |  | simpr 484 | . . . . . 6
⊢ ((𝜑 ∧ 𝑙 ∈ ((𝐹 ↾ (-∞(,)𝑋)) limℂ 𝑋)) → 𝑙 ∈ ((𝐹 ↾ (-∞(,)𝑋)) limℂ 𝑋)) | 
| 15 | 10 | simprd 495 | . . . . . . . . . 10
⊢ (𝜑 → ((𝐹 ↾ (𝑋(,)+∞)) limℂ 𝑋) ≠ ∅) | 
| 16 |  | n0 4353 | . . . . . . . . . 10
⊢ (((𝐹 ↾ (𝑋(,)+∞)) limℂ 𝑋) ≠ ∅ ↔
∃𝑟 𝑟 ∈ ((𝐹 ↾ (𝑋(,)+∞)) limℂ 𝑋)) | 
| 17 | 15, 16 | sylib 218 | . . . . . . . . 9
⊢ (𝜑 → ∃𝑟 𝑟 ∈ ((𝐹 ↾ (𝑋(,)+∞)) limℂ 𝑋)) | 
| 18 | 17 | adantr 480 | . . . . . . . 8
⊢ ((𝜑 ∧ 𝑙 ∈ ((𝐹 ↾ (-∞(,)𝑋)) limℂ 𝑋)) → ∃𝑟 𝑟 ∈ ((𝐹 ↾ (𝑋(,)+∞)) limℂ 𝑋)) | 
| 19 |  | simpr 484 | . . . . . . . . . . 11
⊢ (((𝜑 ∧ 𝑙 ∈ ((𝐹 ↾ (-∞(,)𝑋)) limℂ 𝑋)) ∧ 𝑟 ∈ ((𝐹 ↾ (𝑋(,)+∞)) limℂ 𝑋)) → 𝑟 ∈ ((𝐹 ↾ (𝑋(,)+∞)) limℂ 𝑋)) | 
| 20 | 1 | ad2antrr 726 | . . . . . . . . . . . 12
⊢ (((𝜑 ∧ 𝑙 ∈ ((𝐹 ↾ (-∞(,)𝑋)) limℂ 𝑋)) ∧ 𝑟 ∈ ((𝐹 ↾ (𝑋(,)+∞)) limℂ 𝑋)) → 𝐹:ℝ⟶ℝ) | 
| 21 | 3 | ad4ant14 752 | . . . . . . . . . . . 12
⊢ ((((𝜑 ∧ 𝑙 ∈ ((𝐹 ↾ (-∞(,)𝑋)) limℂ 𝑋)) ∧ 𝑟 ∈ ((𝐹 ↾ (𝑋(,)+∞)) limℂ 𝑋)) ∧ 𝑥 ∈ ℝ) → (𝐹‘(𝑥 + 𝑇)) = (𝐹‘𝑥)) | 
| 22 | 5 | ad2antrr 726 | . . . . . . . . . . . 12
⊢ (((𝜑 ∧ 𝑙 ∈ ((𝐹 ↾ (-∞(,)𝑋)) limℂ 𝑋)) ∧ 𝑟 ∈ ((𝐹 ↾ (𝑋(,)+∞)) limℂ 𝑋)) → ((-π(,)π)
∖ dom 𝐺) ∈
Fin) | 
| 23 | 6 | ad2antrr 726 | . . . . . . . . . . . 12
⊢ (((𝜑 ∧ 𝑙 ∈ ((𝐹 ↾ (-∞(,)𝑋)) limℂ 𝑋)) ∧ 𝑟 ∈ ((𝐹 ↾ (𝑋(,)+∞)) limℂ 𝑋)) → 𝐺 ∈ (dom 𝐺–cn→ℂ)) | 
| 24 | 7 | ad4ant14 752 | . . . . . . . . . . . 12
⊢ ((((𝜑 ∧ 𝑙 ∈ ((𝐹 ↾ (-∞(,)𝑋)) limℂ 𝑋)) ∧ 𝑟 ∈ ((𝐹 ↾ (𝑋(,)+∞)) limℂ 𝑋)) ∧ 𝑥 ∈ ((-π[,)π) ∖ dom 𝐺)) → ((𝐺 ↾ (𝑥(,)+∞)) limℂ 𝑥) ≠ ∅) | 
| 25 | 8 | ad4ant14 752 | . . . . . . . . . . . 12
⊢ ((((𝜑 ∧ 𝑙 ∈ ((𝐹 ↾ (-∞(,)𝑋)) limℂ 𝑋)) ∧ 𝑟 ∈ ((𝐹 ↾ (𝑋(,)+∞)) limℂ 𝑋)) ∧ 𝑥 ∈ ((-π(,]π) ∖ dom 𝐺)) → ((𝐺 ↾ (-∞(,)𝑥)) limℂ 𝑥) ≠ ∅) | 
| 26 | 9 | ad2antrr 726 | . . . . . . . . . . . 12
⊢ (((𝜑 ∧ 𝑙 ∈ ((𝐹 ↾ (-∞(,)𝑋)) limℂ 𝑋)) ∧ 𝑟 ∈ ((𝐹 ↾ (𝑋(,)+∞)) limℂ 𝑋)) → 𝑋 ∈ ℝ) | 
| 27 | 14 | adantr 480 | . . . . . . . . . . . 12
⊢ (((𝜑 ∧ 𝑙 ∈ ((𝐹 ↾ (-∞(,)𝑋)) limℂ 𝑋)) ∧ 𝑟 ∈ ((𝐹 ↾ (𝑋(,)+∞)) limℂ 𝑋)) → 𝑙 ∈ ((𝐹 ↾ (-∞(,)𝑋)) limℂ 𝑋)) | 
| 28 |  | fourier2.a | . . . . . . . . . . . 12
⊢ 𝐴 = (𝑛 ∈ ℕ0 ↦
(∫(-π(,)π)((𝐹‘𝑥) · (cos‘(𝑛 · 𝑥))) d𝑥 / π)) | 
| 29 |  | fourier2.b | . . . . . . . . . . . 12
⊢ 𝐵 = (𝑛 ∈ ℕ ↦
(∫(-π(,)π)((𝐹‘𝑥) · (sin‘(𝑛 · 𝑥))) d𝑥 / π)) | 
| 30 | 20, 2, 21, 4, 22, 23, 24, 25, 26, 27, 19, 28, 29 | fourierd 46237 | . . . . . . . . . . 11
⊢ (((𝜑 ∧ 𝑙 ∈ ((𝐹 ↾ (-∞(,)𝑋)) limℂ 𝑋)) ∧ 𝑟 ∈ ((𝐹 ↾ (𝑋(,)+∞)) limℂ 𝑋)) → (((𝐴‘0) / 2) + Σ𝑛 ∈ ℕ (((𝐴‘𝑛) · (cos‘(𝑛 · 𝑋))) + ((𝐵‘𝑛) · (sin‘(𝑛 · 𝑋))))) = ((𝑙 + 𝑟) / 2)) | 
| 31 | 19, 30 | jca 511 | . . . . . . . . . 10
⊢ (((𝜑 ∧ 𝑙 ∈ ((𝐹 ↾ (-∞(,)𝑋)) limℂ 𝑋)) ∧ 𝑟 ∈ ((𝐹 ↾ (𝑋(,)+∞)) limℂ 𝑋)) → (𝑟 ∈ ((𝐹 ↾ (𝑋(,)+∞)) limℂ 𝑋) ∧ (((𝐴‘0) / 2) + Σ𝑛 ∈ ℕ (((𝐴‘𝑛) · (cos‘(𝑛 · 𝑋))) + ((𝐵‘𝑛) · (sin‘(𝑛 · 𝑋))))) = ((𝑙 + 𝑟) / 2))) | 
| 32 | 31 | ex 412 | . . . . . . . . 9
⊢ ((𝜑 ∧ 𝑙 ∈ ((𝐹 ↾ (-∞(,)𝑋)) limℂ 𝑋)) → (𝑟 ∈ ((𝐹 ↾ (𝑋(,)+∞)) limℂ 𝑋) → (𝑟 ∈ ((𝐹 ↾ (𝑋(,)+∞)) limℂ 𝑋) ∧ (((𝐴‘0) / 2) + Σ𝑛 ∈ ℕ (((𝐴‘𝑛) · (cos‘(𝑛 · 𝑋))) + ((𝐵‘𝑛) · (sin‘(𝑛 · 𝑋))))) = ((𝑙 + 𝑟) / 2)))) | 
| 33 | 32 | eximdv 1917 | . . . . . . . 8
⊢ ((𝜑 ∧ 𝑙 ∈ ((𝐹 ↾ (-∞(,)𝑋)) limℂ 𝑋)) → (∃𝑟 𝑟 ∈ ((𝐹 ↾ (𝑋(,)+∞)) limℂ 𝑋) → ∃𝑟(𝑟 ∈ ((𝐹 ↾ (𝑋(,)+∞)) limℂ 𝑋) ∧ (((𝐴‘0) / 2) + Σ𝑛 ∈ ℕ (((𝐴‘𝑛) · (cos‘(𝑛 · 𝑋))) + ((𝐵‘𝑛) · (sin‘(𝑛 · 𝑋))))) = ((𝑙 + 𝑟) / 2)))) | 
| 34 | 18, 33 | mpd 15 | . . . . . . 7
⊢ ((𝜑 ∧ 𝑙 ∈ ((𝐹 ↾ (-∞(,)𝑋)) limℂ 𝑋)) → ∃𝑟(𝑟 ∈ ((𝐹 ↾ (𝑋(,)+∞)) limℂ 𝑋) ∧ (((𝐴‘0) / 2) + Σ𝑛 ∈ ℕ (((𝐴‘𝑛) · (cos‘(𝑛 · 𝑋))) + ((𝐵‘𝑛) · (sin‘(𝑛 · 𝑋))))) = ((𝑙 + 𝑟) / 2))) | 
| 35 |  | df-rex 3071 | . . . . . . 7
⊢
(∃𝑟 ∈
((𝐹 ↾ (𝑋(,)+∞))
limℂ 𝑋)(((𝐴‘0) / 2) + Σ𝑛 ∈ ℕ (((𝐴‘𝑛) · (cos‘(𝑛 · 𝑋))) + ((𝐵‘𝑛) · (sin‘(𝑛 · 𝑋))))) = ((𝑙 + 𝑟) / 2) ↔ ∃𝑟(𝑟 ∈ ((𝐹 ↾ (𝑋(,)+∞)) limℂ 𝑋) ∧ (((𝐴‘0) / 2) + Σ𝑛 ∈ ℕ (((𝐴‘𝑛) · (cos‘(𝑛 · 𝑋))) + ((𝐵‘𝑛) · (sin‘(𝑛 · 𝑋))))) = ((𝑙 + 𝑟) / 2))) | 
| 36 | 34, 35 | sylibr 234 | . . . . . 6
⊢ ((𝜑 ∧ 𝑙 ∈ ((𝐹 ↾ (-∞(,)𝑋)) limℂ 𝑋)) → ∃𝑟 ∈ ((𝐹 ↾ (𝑋(,)+∞)) limℂ 𝑋)(((𝐴‘0) / 2) + Σ𝑛 ∈ ℕ (((𝐴‘𝑛) · (cos‘(𝑛 · 𝑋))) + ((𝐵‘𝑛) · (sin‘(𝑛 · 𝑋))))) = ((𝑙 + 𝑟) / 2)) | 
| 37 | 14, 36 | jca 511 | . . . . 5
⊢ ((𝜑 ∧ 𝑙 ∈ ((𝐹 ↾ (-∞(,)𝑋)) limℂ 𝑋)) → (𝑙 ∈ ((𝐹 ↾ (-∞(,)𝑋)) limℂ 𝑋) ∧ ∃𝑟 ∈ ((𝐹 ↾ (𝑋(,)+∞)) limℂ 𝑋)(((𝐴‘0) / 2) + Σ𝑛 ∈ ℕ (((𝐴‘𝑛) · (cos‘(𝑛 · 𝑋))) + ((𝐵‘𝑛) · (sin‘(𝑛 · 𝑋))))) = ((𝑙 + 𝑟) / 2))) | 
| 38 | 37 | ex 412 | . . . 4
⊢ (𝜑 → (𝑙 ∈ ((𝐹 ↾ (-∞(,)𝑋)) limℂ 𝑋) → (𝑙 ∈ ((𝐹 ↾ (-∞(,)𝑋)) limℂ 𝑋) ∧ ∃𝑟 ∈ ((𝐹 ↾ (𝑋(,)+∞)) limℂ 𝑋)(((𝐴‘0) / 2) + Σ𝑛 ∈ ℕ (((𝐴‘𝑛) · (cos‘(𝑛 · 𝑋))) + ((𝐵‘𝑛) · (sin‘(𝑛 · 𝑋))))) = ((𝑙 + 𝑟) / 2)))) | 
| 39 | 38 | eximdv 1917 | . . 3
⊢ (𝜑 → (∃𝑙 𝑙 ∈ ((𝐹 ↾ (-∞(,)𝑋)) limℂ 𝑋) → ∃𝑙(𝑙 ∈ ((𝐹 ↾ (-∞(,)𝑋)) limℂ 𝑋) ∧ ∃𝑟 ∈ ((𝐹 ↾ (𝑋(,)+∞)) limℂ 𝑋)(((𝐴‘0) / 2) + Σ𝑛 ∈ ℕ (((𝐴‘𝑛) · (cos‘(𝑛 · 𝑋))) + ((𝐵‘𝑛) · (sin‘(𝑛 · 𝑋))))) = ((𝑙 + 𝑟) / 2)))) | 
| 40 | 13, 39 | mpd 15 | . 2
⊢ (𝜑 → ∃𝑙(𝑙 ∈ ((𝐹 ↾ (-∞(,)𝑋)) limℂ 𝑋) ∧ ∃𝑟 ∈ ((𝐹 ↾ (𝑋(,)+∞)) limℂ 𝑋)(((𝐴‘0) / 2) + Σ𝑛 ∈ ℕ (((𝐴‘𝑛) · (cos‘(𝑛 · 𝑋))) + ((𝐵‘𝑛) · (sin‘(𝑛 · 𝑋))))) = ((𝑙 + 𝑟) / 2))) | 
| 41 |  | df-rex 3071 | . 2
⊢
(∃𝑙 ∈
((𝐹 ↾
(-∞(,)𝑋))
limℂ 𝑋)∃𝑟 ∈ ((𝐹 ↾ (𝑋(,)+∞)) limℂ 𝑋)(((𝐴‘0) / 2) + Σ𝑛 ∈ ℕ (((𝐴‘𝑛) · (cos‘(𝑛 · 𝑋))) + ((𝐵‘𝑛) · (sin‘(𝑛 · 𝑋))))) = ((𝑙 + 𝑟) / 2) ↔ ∃𝑙(𝑙 ∈ ((𝐹 ↾ (-∞(,)𝑋)) limℂ 𝑋) ∧ ∃𝑟 ∈ ((𝐹 ↾ (𝑋(,)+∞)) limℂ 𝑋)(((𝐴‘0) / 2) + Σ𝑛 ∈ ℕ (((𝐴‘𝑛) · (cos‘(𝑛 · 𝑋))) + ((𝐵‘𝑛) · (sin‘(𝑛 · 𝑋))))) = ((𝑙 + 𝑟) / 2))) | 
| 42 | 40, 41 | sylibr 234 | 1
⊢ (𝜑 → ∃𝑙 ∈ ((𝐹 ↾ (-∞(,)𝑋)) limℂ 𝑋)∃𝑟 ∈ ((𝐹 ↾ (𝑋(,)+∞)) limℂ 𝑋)(((𝐴‘0) / 2) + Σ𝑛 ∈ ℕ (((𝐴‘𝑛) · (cos‘(𝑛 · 𝑋))) + ((𝐵‘𝑛) · (sin‘(𝑛 · 𝑋))))) = ((𝑙 + 𝑟) / 2)) |