Theorem: Quaternion.hasSum_expSeries_of_imaginary
File: Mathlib/Analysis/NormedSpace/QuaternionExponential.lean

tactic: replace hc := hasSum_coe.mpr hc
state_before: q : ℍ
hq : q.re = 0
c s : ℝ
hc : HasSum (fun n => (-1) ^ n * ‖q‖ ^ (2 * n) / ↑(2 * n)!) c
hs : HasSum (fun n => (-1) ^ n * ‖q‖ ^ (2 * n + 1) / ↑(2 * n + 1)!) s
⊢ HasSum (fun n => (expSeries ℝ ℍ n) fun x => q) (↑c + (s / ‖q‖) • q)
state_after: q : ℍ
hq : q.re = 0
c s : ℝ
hs : HasSum (fun n => (-1) ^ n * ‖q‖ ^ (2 * n + 1) / ↑(2 * n + 1)!) s
hc : HasSum (fun a => ↑((-1) ^ a * ‖q‖ ^ (2 * a) / ↑(2 * a)!)) ↑c
⊢ HasSum (fun n => (expSeries ℝ ℍ n) fun x => q) (↑c + (s / ‖q‖) • q)

tactic: replace hs := (hs.div_const ‖q‖).smul_const q
state_before: q : ℍ
hq : q.re = 0
c s : ℝ
hs : HasSum (fun n => (-1) ^ n * ‖q‖ ^ (2 * n + 1) / ↑(2 * n + 1)!) s
hc : HasSum (fun a => ↑((-1) ^ a * ‖q‖ ^ (2 * a) / ↑(2 * a)!)) ↑c
⊢ HasSum (fun n => (expSeries ℝ ℍ n) fun x => q) (↑c + (s / ‖q‖) • q)
state_after: q : ℍ
hq : q.re = 0
c s : ℝ
hc : HasSum (fun a => ↑((-1) ^ a * ‖q‖ ^ (2 * a) / ↑(2 * a)!)) ↑c
hs : HasSum (fun z => ((-1) ^ z * ‖q‖ ^ (2 * z + 1) / ↑(2 * z + 1)! / ‖q‖) • q) ((s / ‖q‖) • q)
⊢ HasSum (fun n => (expSeries ℝ ℍ n) fun x => q) (↑c + (s / ‖q‖) • q)

tactic: refine HasSum.even_add_odd ?_ ?_
state_before: q : ℍ
hq : q.re = 0
c s : ℝ
hc : HasSum (fun a => ↑((-1) ^ a * ‖q‖ ^ (2 * a) / ↑(2 * a)!)) ↑c
hs : HasSum (fun z => ((-1) ^ z * ‖q‖ ^ (2 * z + 1) / ↑(2 * z + 1)! / ‖q‖) • q) ((s / ‖q‖) • q)
⊢ HasSum (fun n => (expSeries ℝ ℍ n) fun x => q) (↑c + (s / ‖q‖) • q)
state_after: case refine_1
q : ℍ
hq : q.re = 0
c s : ℝ
hc : HasSum (fun a => ↑((-1) ^ a * ‖q‖ ^ (2 * a) / ↑(2 * a)!)) ↑c
hs : HasSum (fun z => ((-1) ^ z * ‖q‖ ^ (2 * z + 1) / ↑(2 * z + 1)! / ‖q‖) • q) ((s / ‖q‖) • q)
⊢ HasSum (fun k => (expSeries ℝ ℍ (2 * k)) fun x => q) ↑c

case refine_2
q : ℍ
hq : q.re = 0
c s : ℝ
hc : HasSum (fun a => ↑((-1) ^ a * ‖q‖ ^ (2 * a) / ↑(2 * a)!)) ↑c
hs : HasSum (fun z => ((-1) ^ z * ‖q‖ ^ (2 * z + 1) / ↑(2 * z + 1)! / ‖q‖) • q) ((s / ‖q‖) • q)
⊢ HasSum (fun k => (expSeries ℝ ℍ (2 * k + 1)) fun x => q) ((s / ‖q‖) • q)

tactic: convert hc using 1
state_before: case refine_1
q : ℍ
hq : q.re = 0
c s : ℝ
hc : HasSum (fun a => ↑((-1) ^ a * ‖q‖ ^ (2 * a) / ↑(2 * a)!)) ↑c
hs : HasSum (fun z => ((-1) ^ z * ‖q‖ ^ (2 * z + 1) / ↑(2 * z + 1)! / ‖q‖) • q) ((s / ‖q‖) • q)
⊢ HasSum (fun k => (expSeries ℝ ℍ (2 * k)) fun x => q) ↑c
state_after: case h.e'_5
q : ℍ
hq : q.re = 0
c s : ℝ
hc : HasSum (fun a => ↑((-1) ^ a * ‖q‖ ^ (2 * a) / ↑(2 * a)!)) ↑c
hs : HasSum (fun z => ((-1) ^ z * ‖q‖ ^ (2 * z + 1) / ↑(2 * z + 1)! / ‖q‖) • q) ((s / ‖q‖) • q)
⊢ (fun k => (expSeries ℝ ℍ (2 * k)) fun x => q) = fun a => ↑((-1) ^ a * ‖q‖ ^ (2 * a) / ↑(2 * a)!)

tactic: ext n : 1
state_before: case h.e'_5
q : ℍ
hq : q.re = 0
c s : ℝ
hc : HasSum (fun a => ↑((-1) ^ a * ‖q‖ ^ (2 * a) / ↑(2 * a)!)) ↑c
hs : HasSum (fun z => ((-1) ^ z * ‖q‖ ^ (2 * z + 1) / ↑(2 * z + 1)! / ‖q‖) • q) ((s / ‖q‖) • q)
⊢ (fun k => (expSeries ℝ ℍ (2 * k)) fun x => q) = fun a => ↑((-1) ^ a * ‖q‖ ^ (2 * a) / ↑(2 * a)!)
state_after: case h.e'_5.h
q : ℍ
hq : q.re = 0
c s : ℝ
hc : HasSum (fun a => ↑((-1) ^ a * ‖q‖ ^ (2 * a) / ↑(2 * a)!)) ↑c
hs : HasSum (fun z => ((-1) ^ z * ‖q‖ ^ (2 * z + 1) / ↑(2 * z + 1)! / ‖q‖) • q) ((s / ‖q‖) • q)
n : ℕ
⊢ ((expSeries ℝ ℍ (2 * n)) fun x => q) = ↑((-1) ^ n * ‖q‖ ^ (2 * n) / ↑(2 * n)!)

tactic: rw [expSeries_even_of_imaginary hq]
state_before: case h.e'_5.h
q : ℍ
hq : q.re = 0
c s : ℝ
hc : HasSum (fun a => ↑((-1) ^ a * ‖q‖ ^ (2 * a) / ↑(2 * a)!)) ↑c
hs : HasSum (fun z => ((-1) ^ z * ‖q‖ ^ (2 * z + 1) / ↑(2 * z + 1)! / ‖q‖) • q) ((s / ‖q‖) • q)
n : ℕ
⊢ ((expSeries ℝ ℍ (2 * n)) fun x => q) = ↑((-1) ^ n * ‖q‖ ^ (2 * n) / ↑(2 * n)!)
state_after: no goals

tactic: convert hs using 1
state_before: case refine_2
q : ℍ
hq : q.re = 0
c s : ℝ
hc : HasSum (fun a => ↑((-1) ^ a * ‖q‖ ^ (2 * a) / ↑(2 * a)!)) ↑c
hs : HasSum (fun z => ((-1) ^ z * ‖q‖ ^ (2 * z + 1) / ↑(2 * z + 1)! / ‖q‖) • q) ((s / ‖q‖) • q)
⊢ HasSum (fun k => (expSeries ℝ ℍ (2 * k + 1)) fun x => q) ((s / ‖q‖) • q)
state_after: case h.e'_5
q : ℍ
hq : q.re = 0
c s : ℝ
hc : HasSum (fun a => ↑((-1) ^ a * ‖q‖ ^ (2 * a) / ↑(2 * a)!)) ↑c
hs : HasSum (fun z => ((-1) ^ z * ‖q‖ ^ (2 * z + 1) / ↑(2 * z + 1)! / ‖q‖) • q) ((s / ‖q‖) • q)
⊢ (fun k => (expSeries ℝ ℍ (2 * k + 1)) fun x => q) = fun z => ((-1) ^ z * ‖q‖ ^ (2 * z + 1) / ↑(2 * z + 1)! / ‖q‖) • q

tactic: ext n : 1
state_before: case h.e'_5
q : ℍ
hq : q.re = 0
c s : ℝ
hc : HasSum (fun a => ↑((-1) ^ a * ‖q‖ ^ (2 * a) / ↑(2 * a)!)) ↑c
hs : HasSum (fun z => ((-1) ^ z * ‖q‖ ^ (2 * z + 1) / ↑(2 * z + 1)! / ‖q‖) • q) ((s / ‖q‖) • q)
⊢ (fun k => (expSeries ℝ ℍ (2 * k + 1)) fun x => q) = fun z => ((-1) ^ z * ‖q‖ ^ (2 * z + 1) / ↑(2 * z + 1)! / ‖q‖) • q
state_after: case h.e'_5.h
q : ℍ
hq : q.re = 0
c s : ℝ
hc : HasSum (fun a => ↑((-1) ^ a * ‖q‖ ^ (2 * a) / ↑(2 * a)!)) ↑c
hs : HasSum (fun z => ((-1) ^ z * ‖q‖ ^ (2 * z + 1) / ↑(2 * z + 1)! / ‖q‖) • q) ((s / ‖q‖) • q)
n : ℕ
⊢ ((expSeries ℝ ℍ (2 * n + 1)) fun x => q) = ((-1) ^ n * ‖q‖ ^ (2 * n + 1) / ↑(2 * n + 1)! / ‖q‖) • q

tactic: rw [expSeries_odd_of_imaginary hq]
state_before: case h.e'_5.h
q : ℍ
hq : q.re = 0
c s : ℝ
hc : HasSum (fun a => ↑((-1) ^ a * ‖q‖ ^ (2 * a) / ↑(2 * a)!)) ↑c
hs : HasSum (fun z => ((-1) ^ z * ‖q‖ ^ (2 * z + 1) / ↑(2 * z + 1)! / ‖q‖) • q) ((s / ‖q‖) • q)
n : ℕ
⊢ ((expSeries ℝ ℍ (2 * n + 1)) fun x => q) = ((-1) ^ n * ‖q‖ ^ (2 * n + 1) / ↑(2 * n + 1)! / ‖q‖) • q
state_after: no goals