Theorem: EulerSine.antideriv_cos_comp_const_mul
File: Mathlib/Analysis/SpecialFunctions/Trigonometric/EulerSineProd.lean

tactic: have a : HasDerivAt (fun y : ℂ => y * (2 * z)) _ x := hasDerivAt_mul_const _
state_before: z : ℂ
n : ℕ
hz : z ≠ 0
x : ℝ
⊢ HasDerivAt (fun y => Complex.sin (2 * z * ↑y) / (2 * z)) (Complex.cos (2 * z * ↑x)) x
state_after: z : ℂ
n : ℕ
hz : z ≠ 0
x : ℝ
a : HasDerivAt (fun y => y * (2 * z)) (2 * z) ↑x
⊢ HasDerivAt (fun y => Complex.sin (2 * z * ↑y) / (2 * z)) (Complex.cos (2 * z * ↑x)) x

tactic: have b : HasDerivAt (fun y : ℂ => Complex.sin (y * (2 * z))) _ x :=
  HasDerivAt.comp (x : ℂ) (Complex.hasDerivAt_sin (x * (2 * z))) a
state_before: z : ℂ
n : ℕ
hz : z ≠ 0
x : ℝ
a : HasDerivAt (fun y => y * (2 * z)) (2 * z) ↑x
⊢ HasDerivAt (fun y => Complex.sin (2 * z * ↑y) / (2 * z)) (Complex.cos (2 * z * ↑x)) x
state_after: z : ℂ
n : ℕ
hz : z ≠ 0
x : ℝ
a : HasDerivAt (fun y => y * (2 * z)) (2 * z) ↑x
b : HasDerivAt (fun y => Complex.sin (y * (2 * z))) (Complex.cos (↑x * (2 * z)) * (2 * z)) ↑x
⊢ HasDerivAt (fun y => Complex.sin (2 * z * ↑y) / (2 * z)) (Complex.cos (2 * z * ↑x)) x

tactic: have c := b.comp_ofReal.div_const (2 * z)
state_before: z : ℂ
n : ℕ
hz : z ≠ 0
x : ℝ
a : HasDerivAt (fun y => y * (2 * z)) (2 * z) ↑x
b : HasDerivAt (fun y => Complex.sin (y * (2 * z))) (Complex.cos (↑x * (2 * z)) * (2 * z)) ↑x
⊢ HasDerivAt (fun y => Complex.sin (2 * z * ↑y) / (2 * z)) (Complex.cos (2 * z * ↑x)) x
state_after: z : ℂ
n : ℕ
hz : z ≠ 0
x : ℝ
a : HasDerivAt (fun y => y * (2 * z)) (2 * z) ↑x
b : HasDerivAt (fun y => Complex.sin (y * (2 * z))) (Complex.cos (↑x * (2 * z)) * (2 * z)) ↑x
c : HasDerivAt (fun x => Complex.sin (↑x * (2 * z)) / (2 * z)) (Complex.cos (↑x * (2 * z)) * (2 * z) / (2 * z)) x
⊢ HasDerivAt (fun y => Complex.sin (2 * z * ↑y) / (2 * z)) (Complex.cos (2 * z * ↑x)) x

tactic: field_simp at c
state_before: z : ℂ
n : ℕ
hz : z ≠ 0
x : ℝ
a : HasDerivAt (fun y => y * (2 * z)) (2 * z) ↑x
b : HasDerivAt (fun y => Complex.sin (y * (2 * z))) (Complex.cos (↑x * (2 * z)) * (2 * z)) ↑x
c : HasDerivAt (fun x => Complex.sin (↑x * (2 * z)) / (2 * z)) (Complex.cos (↑x * (2 * z)) * (2 * z) / (2 * z)) x
⊢ HasDerivAt (fun y => Complex.sin (2 * z * ↑y) / (2 * z)) (Complex.cos (2 * z * ↑x)) x
state_after: z : ℂ
n : ℕ
hz : z ≠ 0
x : ℝ
a : HasDerivAt (fun y => y * (2 * z)) (2 * z) ↑x
b : HasDerivAt (fun y => Complex.sin (y * (2 * z))) (Complex.cos (↑x * (2 * z)) * (2 * z)) ↑x
c : HasDerivAt (fun x => Complex.sin (↑x * (2 * z)) / (2 * z)) (Complex.cos (↑x * (2 * z))) x
⊢ HasDerivAt (fun y => Complex.sin (2 * z * ↑y) / (2 * z)) (Complex.cos (2 * z * ↑x)) x

tactic: simp only [fun y => mul_comm y (2 * z)] at c
state_before: z : ℂ
n : ℕ
hz : z ≠ 0
x : ℝ
a : HasDerivAt (fun y => y * (2 * z)) (2 * z) ↑x
b : HasDerivAt (fun y => Complex.sin (y * (2 * z))) (Complex.cos (↑x * (2 * z)) * (2 * z)) ↑x
c : HasDerivAt (fun x => Complex.sin (↑x * (2 * z)) / (2 * z)) (Complex.cos (↑x * (2 * z))) x
⊢ HasDerivAt (fun y => Complex.sin (2 * z * ↑y) / (2 * z)) (Complex.cos (2 * z * ↑x)) x
state_after: z : ℂ
n : ℕ
hz : z ≠ 0
x : ℝ
a : HasDerivAt (fun y => y * (2 * z)) (2 * z) ↑x
b : HasDerivAt (fun y => Complex.sin (y * (2 * z))) (Complex.cos (↑x * (2 * z)) * (2 * z)) ↑x
c : HasDerivAt (fun x => Complex.sin (2 * z * ↑x) / (2 * z)) (Complex.cos (2 * z * ↑x)) x
⊢ HasDerivAt (fun y => Complex.sin (2 * z * ↑y) / (2 * z)) (Complex.cos (2 * z * ↑x)) x

tactic: exact c
state_before: z : ℂ
n : ℕ
hz : z ≠ 0
x : ℝ
a : HasDerivAt (fun y => y * (2 * z)) (2 * z) ↑x
b : HasDerivAt (fun y => Complex.sin (y * (2 * z))) (Complex.cos (↑x * (2 * z)) * (2 * z)) ↑x
c : HasDerivAt (fun x => Complex.sin (2 * z * ↑x) / (2 * z)) (Complex.cos (2 * z * ↑x)) x
⊢ HasDerivAt (fun y => Complex.sin (2 * z * ↑y) / (2 * z)) (Complex.cos (2 * z * ↑x)) x
state_after: no goals