@@ -75,7 +75,7 @@ theorem verticalIntegral_norm_le (hb : 0 < b.re) (c : ℝ) {T : ℝ} (hT : 0 ≤
7575 exp (-(b.re * T ^ 2 - (2 : ℝ) * |b.im| * |c| * T - b.re * c ^ 2 )) := by
7676 intro T hT c y hy
7777 rw [norm_cexp_neg_mul_sq_add_mul_I b]
78- gcongr exp (- (_ - ?_ * _ - _ * ?_))
78+ gcongr exp (-(_ - ?_ * _ - _ * ?_))
7979 · (conv_lhs => rw [mul_assoc]); (conv_rhs => rw [mul_assoc])
8080 gcongr _ * ?_
8181 refine (le_abs_self _).trans ?_
@@ -177,7 +177,8 @@ theorem integral_cexp_neg_mul_sq_add_real_mul_I (hb : 0 < b.re) (c : ℝ) :
177177 tendsto_id
178178
179179theorem _root_.integral_cexp_quadratic (hb : b.re < 0 ) (c d : ℂ) :
180- ∫ x : ℝ, cexp (b * x ^ 2 + c * x + d) = (π / -b) ^ (1 / 2 : ℂ) * cexp (d - c^2 / (4 * b)) := by
180+ ∫ x : ℝ,
181+ cexp (b * x ^ 2 + c * x + d) = (π / -b) ^ (1 / 2 : ℂ) * cexp (d - c ^ 2 / (4 * b)) := by
181182 have hb' : b ≠ 0 := by contrapose! hb; rw [hb, zero_re]
182183 have h (x : ℝ) : cexp (b * x ^ 2 + c * x + d) =
183184 cexp (- -b * (x + c / (2 * b)) ^ 2 ) * cexp (d - c ^ 2 / (4 * b)) := by
@@ -242,20 +243,20 @@ variable {V : Type*} [NormedAddCommGroup V] [InnerProductSpace ℝ V] [FiniteDim
242243
243244theorem integrable_cexp_neg_sum_mul_add {ι : Type *} [Fintype ι] {b : ι → ℂ}
244245 (hb : ∀ i, 0 < (b i).re) (c : ι → ℂ) :
245- Integrable (fun (v : ι → ℝ) ↦ cexp (- ∑ i, b i * (v i : ℂ) ^ 2 + ∑ i, c i * v i)) := by
246+ Integrable (fun (v : ι → ℝ) ↦ cexp (-∑ i, b i * (v i : ℂ) ^ 2 + ∑ i, c i * v i)) := by
246247 simp_rw [← Finset.sum_neg_distrib, ← Finset.sum_add_distrib, Complex.exp_sum, ← neg_mul]
247- apply Integrable.fintype_prod (f := fun i (v : ℝ) ↦ cexp (-b i * v^ 2 + c i * v)) (fun i ↦ ?_)
248+ apply Integrable.fintype_prod (f := fun i (v : ℝ) ↦ cexp (-b i * v ^ 2 + c i * v)) (fun i ↦ ?_)
248249 convert integrable_cexp_quadratic (hb i) (c i) 0 using 3 with x
249250 simp only [add_zero]
250251
251252theorem integrable_cexp_neg_mul_sum_add {ι : Type *} [Fintype ι] (hb : 0 < b.re) (c : ι → ℂ) :
252- Integrable (fun (v : ι → ℝ) ↦ cexp (- b * ∑ i, (v i : ℂ) ^ 2 + ∑ i, c i * v i)) := by
253+ Integrable (fun (v : ι → ℝ) ↦ cexp (-b * ∑ i, (v i : ℂ) ^ 2 + ∑ i, c i * v i)) := by
253254 simp_rw [neg_mul, Finset.mul_sum]
254255 exact integrable_cexp_neg_sum_mul_add (fun _ ↦ hb) c
255256
256257theorem integrable_cexp_neg_mul_sq_norm_add_of_euclideanSpace
257258 {ι : Type *} [Fintype ι] (hb : 0 < b.re) (c : ℂ) (w : EuclideanSpace ℝ ι) :
258- Integrable (fun (v : EuclideanSpace ℝ ι) ↦ cexp (- b * ‖v‖^ 2 + c * ⟪w, v⟫)) := by
259+ Integrable (fun (v : EuclideanSpace ℝ ι) ↦ cexp (-b * ‖v‖ ^ 2 + c * ⟪w, v⟫)) := by
259260 have := EuclideanSpace.volume_preserving_measurableEquiv ι
260261 rw [← MeasurePreserving.integrable_comp_emb this.symm (MeasurableEquiv.measurableEmbedding _)]
261262 simp only [neg_mul, Function.comp_def]
@@ -272,7 +273,7 @@ theorem integrable_cexp_neg_mul_sq_norm_add_of_euclideanSpace
272273/-- In a real inner product space, the complex exponential of minus the square of the norm plus
273274a scalar product is integrable. Useful when discussing the Fourier transform of a Gaussian. -/
274275theorem integrable_cexp_neg_mul_sq_norm_add (hb : 0 < b.re) (c : ℂ) (w : V) :
275- Integrable (fun (v : V) ↦ cexp (-b * ‖v‖^ 2 + c * ⟪w, v⟫)) := by
276+ Integrable (fun (v : V) ↦ cexp (-b * ‖v‖ ^ 2 + c * ⟪w, v⟫)) := by
276277 let e := (stdOrthonormalBasis ℝ V).repr.symm
277278 rw [← e.measurePreserving.integrable_comp_emb e.toHomeomorph.measurableEmbedding]
278279 convert integrable_cexp_neg_mul_sq_norm_add_of_euclideanSpace
@@ -283,7 +284,7 @@ theorem integrable_cexp_neg_mul_sq_norm_add (hb : 0 < b.re) (c : ℂ) (w : V) :
283284
284285theorem integral_cexp_neg_sum_mul_add {ι : Type *} [Fintype ι] {b : ι → ℂ}
285286 (hb : ∀ i, 0 < (b i).re) (c : ι → ℂ) :
286- ∫ v : ι → ℝ, cexp (- ∑ i, b i * (v i : ℂ) ^ 2 + ∑ i, c i * v i)
287+ ∫ v : ι → ℝ, cexp (-∑ i, b i * (v i : ℂ) ^ 2 + ∑ i, c i * v i)
287288 = ∏ i, (π / b i) ^ (1 / 2 : ℂ) * cexp (c i ^ 2 / (4 * b i)) := by
288289 simp_rw [← Finset.sum_neg_distrib, ← Finset.sum_add_distrib, Complex.exp_sum, ← neg_mul]
289290 rw [integral_fintype_prod_volume_eq_prod (f := fun i (v : ℝ) ↦ cexp (-b i * v ^ 2 + c i * v))]
@@ -292,16 +293,16 @@ theorem integral_cexp_neg_sum_mul_add {ι : Type*} [Fintype ι] {b : ι → ℂ}
292293 convert integral_cexp_quadratic this (c i) 0 using 1 <;> simp [div_neg]
293294
294295theorem integral_cexp_neg_mul_sum_add {ι : Type *} [Fintype ι] (hb : 0 < b.re) (c : ι → ℂ) :
295- ∫ v : ι → ℝ, cexp (- b * ∑ i, (v i : ℂ) ^ 2 + ∑ i, c i * v i)
296+ ∫ v : ι → ℝ, cexp (-b * ∑ i, (v i : ℂ) ^ 2 + ∑ i, c i * v i)
296297 = (π / b) ^ (Fintype.card ι / 2 : ℂ) * cexp ((∑ i, c i ^ 2 ) / (4 * b)) := by
297298 simp_rw [neg_mul, Finset.mul_sum, integral_cexp_neg_sum_mul_add (fun _ ↦ hb) c, one_div,
298299 Finset.prod_mul_distrib, Finset.prod_const, ← cpow_nat_mul, ← Complex.exp_sum, Fintype.card,
299300 Finset.sum_div, div_eq_mul_inv]
300301
301302theorem integral_cexp_neg_mul_sq_norm_add_of_euclideanSpace
302303 {ι : Type *} [Fintype ι] (hb : 0 < b.re) (c : ℂ) (w : EuclideanSpace ℝ ι) :
303- ∫ v : EuclideanSpace ℝ ι, cexp (- b * ‖v‖^ 2 + c * ⟪w, v⟫) =
304- (π / b) ^ (Fintype.card ι / 2 : ℂ) * cexp (c ^ 2 * ‖w‖^ 2 / (4 * b)) := by
304+ ∫ v : EuclideanSpace ℝ ι, cexp (-b * ‖v‖ ^ 2 + c * ⟪w, v⟫) =
305+ (π / b) ^ (Fintype.card ι / 2 : ℂ) * cexp (c ^ 2 * ‖w‖ ^ 2 / (4 * b)) := by
305306 have := (EuclideanSpace.volume_preserving_measurableEquiv ι).symm
306307 rw [← this.integral_comp (MeasurableEquiv.measurableEmbedding _)]
307308 simp only [neg_mul]
@@ -322,19 +323,19 @@ theorem integral_cexp_neg_mul_sq_norm_add_of_euclideanSpace
322323
323324theorem integral_cexp_neg_mul_sq_norm_add
324325 (hb : 0 < b.re) (c : ℂ) (w : V) :
325- ∫ v : V, cexp (- b * ‖v‖^ 2 + c * ⟪w, v⟫) =
326- (π / b) ^ (Module.finrank ℝ V / 2 : ℂ) * cexp (c ^ 2 * ‖w‖^ 2 / (4 * b)) := by
326+ ∫ v : V, cexp (-b * ‖v‖ ^ 2 + c * ⟪w, v⟫) =
327+ (π / b) ^ (Module.finrank ℝ V / 2 : ℂ) * cexp (c ^ 2 * ‖w‖ ^ 2 / (4 * b)) := by
327328 let e := (stdOrthonormalBasis ℝ V).repr.symm
328329 rw [← e.measurePreserving.integral_comp e.toHomeomorph.measurableEmbedding]
329330 convert integral_cexp_neg_mul_sq_norm_add_of_euclideanSpace
330331 hb c (e.symm w) <;> simp [LinearIsometryEquiv.inner_map_eq_flip]
331332
332333theorem integral_cexp_neg_mul_sq_norm (hb : 0 < b.re) :
333- ∫ v : V, cexp (- b * ‖v‖^ 2 ) = (π / b) ^ (Module.finrank ℝ V / 2 : ℂ) := by
334+ ∫ v : V, cexp (-b * ‖v‖ ^ 2 ) = (π / b) ^ (Module.finrank ℝ V / 2 : ℂ) := by
334335 simpa using integral_cexp_neg_mul_sq_norm_add hb 0 (0 : V)
335336
336337theorem integral_rexp_neg_mul_sq_norm {b : ℝ} (hb : 0 < b) :
337- ∫ v : V, rexp (- b * ‖v‖^ 2 ) = (π / b) ^ (Module.finrank ℝ V / 2 : ℝ) := by
338+ ∫ v : V, rexp (-b * ‖v‖ ^ 2 ) = (π / b) ^ (Module.finrank ℝ V / 2 : ℝ) := by
338339 rw [← ofReal_inj]
339340 convert integral_cexp_neg_mul_sq_norm (show 0 < (b : ℂ).re from hb) (V := V)
340341 · change ofRealLI (∫ (v : V), rexp (-b * ‖v‖ ^ 2 )) = ∫ (v : V), cexp (-↑b * ↑‖v‖ ^ 2 )
@@ -344,7 +345,7 @@ theorem integral_rexp_neg_mul_sq_norm {b : ℝ} (hb : 0 < b) :
344345 simp
345346
346347theorem _root_.fourierIntegral_gaussian_innerProductSpace' (hb : 0 < b.re) (x w : V) :
347- 𝓕 (fun v ↦ cexp (- b * ‖v‖^ 2 + 2 * π * Complex.I * ⟪x, v⟫)) w =
348+ 𝓕 (fun v ↦ cexp (-b * ‖v‖ ^ 2 + 2 * π * Complex.I * ⟪x, v⟫)) w =
348349 (π / b) ^ (Module.finrank ℝ V / 2 : ℂ) * cexp (-π ^ 2 * ‖x - w‖ ^ 2 / b) := by
349350 simp only [neg_mul, fourierIntegral_eq', ofReal_neg, ofReal_mul, ofReal_ofNat,
350351 smul_eq_mul, ← Complex.exp_add, real_inner_comm w]
@@ -357,8 +358,8 @@ theorem _root_.fourierIntegral_gaussian_innerProductSpace' (hb : 0 < b.re) (x w
357358 ring
358359
359360theorem _root_.fourierIntegral_gaussian_innerProductSpace (hb : 0 < b.re) (w : V) :
360- 𝓕 (fun v ↦ cexp (- b * ‖v‖^ 2 )) w =
361- (π / b) ^ (Module.finrank ℝ V / 2 : ℂ) * cexp (-π ^ 2 * ‖w‖^ 2 / b) := by
361+ 𝓕 (fun v ↦ cexp (-b * ‖v‖ ^ 2 )) w =
362+ (π / b) ^ (Module.finrank ℝ V / 2 : ℂ) * cexp (-π ^ 2 * ‖w‖ ^ 2 / b) := by
362363 simpa using fourierIntegral_gaussian_innerProductSpace' hb 0 w
363364
364365end InnerProductSpace
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