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| Mirrors > Home > ILE Home > Th. List > df-abs | GIF version | ||
| Description: Define the function for the absolute value (modulus) of a complex number. (Contributed by NM, 27-Jul-1999.) | 
| Ref | Expression | 
|---|---|
| df-abs | ⊢ abs = (𝑥 ∈ ℂ ↦ (√‘(𝑥 · (∗‘𝑥)))) | 
| Step | Hyp | Ref | Expression | 
|---|---|---|---|
| 1 | cabs 11162 | . 2 class abs | |
| 2 | vx | . . 3 setvar 𝑥 | |
| 3 | cc 7877 | . . 3 class ℂ | |
| 4 | 2 | cv 1363 | . . . . 5 class 𝑥 | 
| 5 | ccj 11004 | . . . . . 6 class ∗ | |
| 6 | 4, 5 | cfv 5258 | . . . . 5 class (∗‘𝑥) | 
| 7 | cmul 7884 | . . . . 5 class · | |
| 8 | 4, 6, 7 | co 5922 | . . . 4 class (𝑥 · (∗‘𝑥)) | 
| 9 | csqrt 11161 | . . . 4 class √ | |
| 10 | 8, 9 | cfv 5258 | . . 3 class (√‘(𝑥 · (∗‘𝑥))) | 
| 11 | 2, 3, 10 | cmpt 4094 | . 2 class (𝑥 ∈ ℂ ↦ (√‘(𝑥 · (∗‘𝑥)))) | 
| 12 | 1, 11 | wceq 1364 | 1 wff abs = (𝑥 ∈ ℂ ↦ (√‘(𝑥 · (∗‘𝑥)))) | 
| Colors of variables: wff set class | 
| This definition is referenced by: absval 11166 absf 11275 cndsex 14109 | 
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