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Definition df-sec 42256
Description: Define the secant function. We define it this way for cmpt 4727, which requires the form (𝑥𝐴𝐵). The sec function is defined in ISO 80000-2:2009(E) operation 2-13.6 and "NIST Digital Library of Mathematical Functions" section on "Trigonometric Functions" http://dlmf.nist.gov/4.14 (Contributed by David A. Wheeler, 14-Mar-2014.)
Assertion
Ref Expression
df-sec sec = (𝑥 ∈ {𝑦 ∈ ℂ ∣ (cos‘𝑦) ≠ 0} ↦ (1 / (cos‘𝑥)))
Distinct variable group:   𝑥,𝑦

Detailed syntax breakdown of Definition df-sec
StepHypRef Expression
1 csec 42253 . 2 class sec
2 vx . . 3 setvar 𝑥
3 vy . . . . . . 7 setvar 𝑦
43cv 1481 . . . . . 6 class 𝑦
5 ccos 14789 . . . . . 6 class cos
64, 5cfv 5886 . . . . 5 class (cos‘𝑦)
7 cc0 9933 . . . . 5 class 0
86, 7wne 2793 . . . 4 wff (cos‘𝑦) ≠ 0
9 cc 9931 . . . 4 class
108, 3, 9crab 2915 . . 3 class {𝑦 ∈ ℂ ∣ (cos‘𝑦) ≠ 0}
11 c1 9934 . . . 4 class 1
122cv 1481 . . . . 5 class 𝑥
1312, 5cfv 5886 . . . 4 class (cos‘𝑥)
14 cdiv 10681 . . . 4 class /
1511, 13, 14co 6647 . . 3 class (1 / (cos‘𝑥))
162, 10, 15cmpt 4727 . 2 class (𝑥 ∈ {𝑦 ∈ ℂ ∣ (cos‘𝑦) ≠ 0} ↦ (1 / (cos‘𝑥)))
171, 16wceq 1482 1 wff sec = (𝑥 ∈ {𝑦 ∈ ℂ ∣ (cos‘𝑦) ≠ 0} ↦ (1 / (cos‘𝑥)))
Colors of variables: wff setvar class
This definition is referenced by:  secval  42259
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