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re_inner_eq_norm_add_mul_self_sub_norm_mul_self_sub_norm_mul_self_div_two (x y : E) : re ⟪x, y⟫ = (‖x + y‖ * ‖x + y‖ - ‖x‖ * ‖x‖ - ‖y‖ * ‖y‖) / 2
by { rw @norm_add_mul_self 𝕜, ring }
lemma
re_inner_eq_norm_add_mul_self_sub_norm_mul_self_sub_norm_mul_self_div_two
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "norm_add_mul_self", "ring" ]
Polarization identity: The real part of the inner product, in terms of the norm.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
re_inner_eq_norm_mul_self_add_norm_mul_self_sub_norm_sub_mul_self_div_two (x y : E) : re ⟪x, y⟫ = (‖x‖ * ‖x‖ + ‖y‖ * ‖y‖ - ‖x - y‖ * ‖x - y‖) / 2
by { rw [@norm_sub_mul_self 𝕜], ring }
lemma
re_inner_eq_norm_mul_self_add_norm_mul_self_sub_norm_sub_mul_self_div_two
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "norm_sub_mul_self", "ring" ]
Polarization identity: The real part of the inner product, in terms of the norm.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
re_inner_eq_norm_add_mul_self_sub_norm_sub_mul_self_div_four (x y : E) : re ⟪x, y⟫ = (‖x + y‖ * ‖x + y‖ - ‖x - y‖ * ‖x - y‖) / 4
by { rw [@norm_add_mul_self 𝕜, @norm_sub_mul_self 𝕜], ring }
lemma
re_inner_eq_norm_add_mul_self_sub_norm_sub_mul_self_div_four
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "norm_add_mul_self", "norm_sub_mul_self", "ring" ]
Polarization identity: The real part of the inner product, in terms of the norm.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
im_inner_eq_norm_sub_I_smul_mul_self_sub_norm_add_I_smul_mul_self_div_four (x y : E) : im ⟪x, y⟫ = (‖x - IK • y‖ * ‖x - IK • y‖ - ‖x + IK • y‖ * ‖x + IK • y‖) / 4
by { simp only [@norm_add_mul_self 𝕜, @norm_sub_mul_self 𝕜, inner_smul_right, I_mul_re], ring }
lemma
im_inner_eq_norm_sub_I_smul_mul_self_sub_norm_add_I_smul_mul_self_div_four
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "inner_smul_right", "norm_add_mul_self", "norm_sub_mul_self", "ring" ]
Polarization identity: The imaginary part of the inner product, in terms of the norm.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
inner_eq_sum_norm_sq_div_four (x y : E) : ⟪x, y⟫ = (‖x + y‖ ^ 2 - ‖x - y‖ ^ 2 + (‖x - IK • y‖ ^ 2 - ‖x + IK • y‖ ^ 2) * IK) / 4
begin rw [← re_add_im ⟪x, y⟫, re_inner_eq_norm_add_mul_self_sub_norm_sub_mul_self_div_four, im_inner_eq_norm_sub_I_smul_mul_self_sub_norm_add_I_smul_mul_self_div_four], push_cast, simp only [sq, ← mul_div_right_comm, ← add_div] end
lemma
inner_eq_sum_norm_sq_div_four
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "add_div", "im_inner_eq_norm_sub_I_smul_mul_self_sub_norm_add_I_smul_mul_self_div_four", "mul_div_right_comm", "re_inner_eq_norm_add_mul_self_sub_norm_sub_mul_self_div_four" ]
Polarization identity: The inner product, in terms of the norm.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
dist_div_norm_sq_smul {x y : F} (hx : x ≠ 0) (hy : y ≠ 0) (R : ℝ) : dist ((R / ‖x‖) ^ 2 • x) ((R / ‖y‖) ^ 2 • y) = (R ^ 2 / (‖x‖ * ‖y‖)) * dist x y
have hx' : ‖x‖ ≠ 0, from norm_ne_zero_iff.2 hx, have hy' : ‖y‖ ≠ 0, from norm_ne_zero_iff.2 hy, calc dist ((R / ‖x‖) ^ 2 • x) ((R / ‖y‖) ^ 2 • y) = sqrt (‖(R / ‖x‖) ^ 2 • x - (R / ‖y‖) ^ 2 • y‖^2) : by rw [dist_eq_norm, sqrt_sq (norm_nonneg _)] ... = sqrt ((R ^ 2 / (‖x‖ * ‖y‖)) ^ 2 * ‖x - y‖ ^ 2) : congr_arg sq...
lemma
dist_div_norm_sq_smul
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "div_nonneg", "inner_smul_right", "mul_self_nonneg", "norm_smul", "norm_sub_mul_self_real", "real.norm_of_nonneg", "real_inner_smul_left", "ring", "sq_nonneg" ]
Formula for the distance between the images of two nonzero points under an inversion with center zero. See also `euclidean_geometry.dist_inversion_inversion` for inversions around a general point.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
inner_product_space.to_uniform_convex_space : uniform_convex_space F
⟨λ ε hε, begin refine ⟨2 - sqrt (4 - ε^2), sub_pos_of_lt $ (sqrt_lt' zero_lt_two).2 _, λ x hx y hy hxy, _⟩, { norm_num, exact pow_pos hε _ }, rw sub_sub_cancel, refine le_sqrt_of_sq_le _, rw [sq, eq_sub_iff_add_eq.2 (parallelogram_law_with_norm ℝ x y), ←sq (‖x - y‖), hx, hy], norm_num, exact pow_le_po...
instance
inner_product_space.to_uniform_convex_space
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "parallelogram_law_with_norm", "pow_le_pow_of_le_left", "pow_pos", "uniform_convex_space", "zero_lt_two" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
inner_map_polarization (T : V →ₗ[ℂ] V) (x y : V): ⟪ T y, x ⟫_ℂ = (⟪T (x + y) , x + y⟫_ℂ - ⟪T (x - y) , x - y⟫_ℂ + complex.I * ⟪T (x + complex.I • y) , x + complex.I • y⟫_ℂ - complex.I * ⟪T (x - complex.I • y), x - complex.I • y ⟫_ℂ) / 4
begin simp only [map_add, map_sub, inner_add_left, inner_add_right, linear_map.map_smul, inner_smul_left, inner_smul_right, complex.conj_I, ←pow_two, complex.I_sq, inner_sub_left, inner_sub_right, mul_add, ←mul_assoc, mul_neg, neg_neg, sub_neg_eq_add, one_mul, neg_one_mul, mul_s...
lemma
inner_map_polarization
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "complex.I", "complex.I_sq", "complex.conj_I", "inner_add_left", "inner_add_right", "inner_smul_left", "inner_smul_right", "inner_sub_left", "inner_sub_right", "linear_map.map_smul", "mul_neg", "neg_one_mul", "one_mul", "ring" ]
A complex polarization identity, with a linear map
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
inner_map_polarization' (T : V →ₗ[ℂ] V) (x y : V): ⟪ T x, y ⟫_ℂ = (⟪T (x + y) , x + y⟫_ℂ - ⟪T (x - y) , x - y⟫_ℂ - complex.I * ⟪T (x + complex.I • y) , x + complex.I • y⟫_ℂ + complex.I * ⟪T (x - complex.I • y), x - complex.I • y ⟫_ℂ) / 4
begin simp only [map_add, map_sub, inner_add_left, inner_add_right, linear_map.map_smul, inner_smul_left, inner_smul_right, complex.conj_I, ←pow_two, complex.I_sq, inner_sub_left, inner_sub_right, mul_add, ←mul_assoc, mul_neg, neg_neg, sub_neg_eq_add, one_mul, neg_one_mul, mul_s...
lemma
inner_map_polarization'
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "complex.I", "complex.I_sq", "complex.conj_I", "inner_add_left", "inner_add_right", "inner_smul_left", "inner_smul_right", "inner_sub_left", "inner_sub_right", "linear_map.map_smul", "mul_neg", "neg_one_mul", "one_mul", "ring" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
inner_map_self_eq_zero (T : V →ₗ[ℂ] V) : (∀ (x : V), ⟪T x, x⟫_ℂ = 0) ↔ T = 0
begin split, { intro hT, ext x, simp only [linear_map.zero_apply, ← @inner_self_eq_zero ℂ, inner_map_polarization, hT], norm_num }, { rintro rfl x, simp only [linear_map.zero_apply, inner_zero_left] } end
lemma
inner_map_self_eq_zero
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "inner_map_polarization", "inner_self_eq_zero", "inner_zero_left", "linear_map.zero_apply" ]
A linear map `T` is zero, if and only if the identity `⟪T x, x⟫_ℂ = 0` holds for all `x`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
ext_inner_map (S T : V →ₗ[ℂ] V) : (∀ (x : V), ⟪S x, x⟫_ℂ = ⟪T x, x⟫_ℂ) ↔ S = T
begin rw [←sub_eq_zero, ←inner_map_self_eq_zero], refine forall_congr (λ x, _), rw [linear_map.sub_apply, inner_sub_left, sub_eq_zero], end
lemma
ext_inner_map
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "inner_sub_left", "linear_map.sub_apply" ]
Two linear maps `S` and `T` are equal, if and only if the identity `⟪S x, x⟫_ℂ = ⟪T x, x⟫_ℂ` holds for all `x`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
linear_isometry.inner_map_map (f : E →ₗᵢ[𝕜] E') (x y : E) : ⟪f x, f y⟫ = ⟪x, y⟫
by simp [inner_eq_sum_norm_sq_div_four, ← f.norm_map]
lemma
linear_isometry.inner_map_map
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "inner_eq_sum_norm_sq_div_four" ]
A linear isometry preserves the inner product.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
linear_isometry_equiv.inner_map_map (f : E ≃ₗᵢ[𝕜] E') (x y : E) : ⟪f x, f y⟫ = ⟪x, y⟫
f.to_linear_isometry.inner_map_map x y
lemma
linear_isometry_equiv.inner_map_map
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[]
A linear isometric equivalence preserves the inner product.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
linear_map.isometry_of_inner (f : E →ₗ[𝕜] E') (h : ∀ x y, ⟪f x, f y⟫ = ⟪x, y⟫) : E →ₗᵢ[𝕜] E'
⟨f, λ x, by simp only [@norm_eq_sqrt_inner 𝕜, h]⟩
def
linear_map.isometry_of_inner
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "norm_eq_sqrt_inner" ]
A linear map that preserves the inner product is a linear isometry.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
linear_map.coe_isometry_of_inner (f : E →ₗ[𝕜] E') (h) : ⇑(f.isometry_of_inner h) = f
rfl
lemma
linear_map.coe_isometry_of_inner
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
linear_map.isometry_of_inner_to_linear_map (f : E →ₗ[𝕜] E') (h) : (f.isometry_of_inner h).to_linear_map = f
rfl
lemma
linear_map.isometry_of_inner_to_linear_map
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
linear_equiv.isometry_of_inner (f : E ≃ₗ[𝕜] E') (h : ∀ x y, ⟪f x, f y⟫ = ⟪x, y⟫) : E ≃ₗᵢ[𝕜] E'
⟨f, ((f : E →ₗ[𝕜] E').isometry_of_inner h).norm_map⟩
def
linear_equiv.isometry_of_inner
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[]
A linear equivalence that preserves the inner product is a linear isometric equivalence.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
linear_equiv.coe_isometry_of_inner (f : E ≃ₗ[𝕜] E') (h) : ⇑(f.isometry_of_inner h) = f
rfl
lemma
linear_equiv.coe_isometry_of_inner
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
linear_equiv.isometry_of_inner_to_linear_equiv (f : E ≃ₗ[𝕜] E') (h) : (f.isometry_of_inner h).to_linear_equiv = f
rfl
lemma
linear_equiv.isometry_of_inner_to_linear_equiv
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
linear_isometry.orthonormal_comp_iff {v : ι → E} (f : E →ₗᵢ[𝕜] E') : orthonormal 𝕜 (f ∘ v) ↔ orthonormal 𝕜 v
begin classical, simp_rw [orthonormal_iff_ite, linear_isometry.inner_map_map] end
lemma
linear_isometry.orthonormal_comp_iff
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "linear_isometry.inner_map_map", "orthonormal", "orthonormal_iff_ite" ]
A linear isometry preserves the property of being orthonormal.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
orthonormal.comp_linear_isometry {v : ι → E} (hv : orthonormal 𝕜 v) (f : E →ₗᵢ[𝕜] E') : orthonormal 𝕜 (f ∘ v)
by rwa f.orthonormal_comp_iff
lemma
orthonormal.comp_linear_isometry
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "orthonormal" ]
A linear isometry preserves the property of being orthonormal.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
orthonormal.comp_linear_isometry_equiv {v : ι → E} (hv : orthonormal 𝕜 v) (f : E ≃ₗᵢ[𝕜] E') : orthonormal 𝕜 (f ∘ v)
hv.comp_linear_isometry f.to_linear_isometry
lemma
orthonormal.comp_linear_isometry_equiv
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "orthonormal" ]
A linear isometric equivalence preserves the property of being orthonormal.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
orthonormal.map_linear_isometry_equiv {v : basis ι 𝕜 E} (hv : orthonormal 𝕜 v) (f : E ≃ₗᵢ[𝕜] E') : orthonormal 𝕜 (v.map f.to_linear_equiv)
hv.comp_linear_isometry_equiv f
lemma
orthonormal.map_linear_isometry_equiv
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "basis", "orthonormal" ]
A linear isometric equivalence, applied with `basis.map`, preserves the property of being orthonormal.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
linear_map.isometry_of_orthonormal (f : E →ₗ[𝕜] E') {v : basis ι 𝕜 E} (hv : orthonormal 𝕜 v) (hf : orthonormal 𝕜 (f ∘ v)) : E →ₗᵢ[𝕜] E'
f.isometry_of_inner $ λ x y, by rw [←v.total_repr x, ←v.total_repr y, finsupp.apply_total, finsupp.apply_total, hv.inner_finsupp_eq_sum_left, hf.inner_finsupp_eq_sum_left]
def
linear_map.isometry_of_orthonormal
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "basis", "finsupp.apply_total", "orthonormal" ]
A linear map that sends an orthonormal basis to orthonormal vectors is a linear isometry.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
linear_map.coe_isometry_of_orthonormal (f : E →ₗ[𝕜] E') {v : basis ι 𝕜 E} (hv : orthonormal 𝕜 v) (hf : orthonormal 𝕜 (f ∘ v)) : ⇑(f.isometry_of_orthonormal hv hf) = f
rfl
lemma
linear_map.coe_isometry_of_orthonormal
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "basis", "orthonormal" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
linear_map.isometry_of_orthonormal_to_linear_map (f : E →ₗ[𝕜] E') {v : basis ι 𝕜 E} (hv : orthonormal 𝕜 v) (hf : orthonormal 𝕜 (f ∘ v)) : (f.isometry_of_orthonormal hv hf).to_linear_map = f
rfl
lemma
linear_map.isometry_of_orthonormal_to_linear_map
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "basis", "orthonormal" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
linear_equiv.isometry_of_orthonormal (f : E ≃ₗ[𝕜] E') {v : basis ι 𝕜 E} (hv : orthonormal 𝕜 v) (hf : orthonormal 𝕜 (f ∘ v)) : E ≃ₗᵢ[𝕜] E'
f.isometry_of_inner $ λ x y, begin rw ←linear_equiv.coe_coe at hf, rw [←v.total_repr x, ←v.total_repr y, ←linear_equiv.coe_coe, finsupp.apply_total, finsupp.apply_total, hv.inner_finsupp_eq_sum_left, hf.inner_finsupp_eq_sum_left] end
def
linear_equiv.isometry_of_orthonormal
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "basis", "finsupp.apply_total", "orthonormal" ]
A linear equivalence that sends an orthonormal basis to orthonormal vectors is a linear isometric equivalence.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
linear_equiv.coe_isometry_of_orthonormal (f : E ≃ₗ[𝕜] E') {v : basis ι 𝕜 E} (hv : orthonormal 𝕜 v) (hf : orthonormal 𝕜 (f ∘ v)) : ⇑(f.isometry_of_orthonormal hv hf) = f
rfl
lemma
linear_equiv.coe_isometry_of_orthonormal
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "basis", "orthonormal" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
linear_equiv.isometry_of_orthonormal_to_linear_equiv (f : E ≃ₗ[𝕜] E') {v : basis ι 𝕜 E} (hv : orthonormal 𝕜 v) (hf : orthonormal 𝕜 (f ∘ v)) : (f.isometry_of_orthonormal hv hf).to_linear_equiv = f
rfl
lemma
linear_equiv.isometry_of_orthonormal_to_linear_equiv
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "basis", "orthonormal" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
orthonormal.equiv {v : basis ι 𝕜 E} (hv : orthonormal 𝕜 v) {v' : basis ι' 𝕜 E'} (hv' : orthonormal 𝕜 v') (e : ι ≃ ι') : E ≃ₗᵢ[𝕜] E'
(v.equiv v' e).isometry_of_orthonormal hv begin have h : (v.equiv v' e) ∘ v = v' ∘ e, { ext i, simp }, rw h, exact hv'.comp _ e.injective end
def
orthonormal.equiv
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "basis", "orthonormal" ]
A linear isometric equivalence that sends an orthonormal basis to a given orthonormal basis.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
orthonormal.equiv_to_linear_equiv {v : basis ι 𝕜 E} (hv : orthonormal 𝕜 v) {v' : basis ι' 𝕜 E'} (hv' : orthonormal 𝕜 v') (e : ι ≃ ι') : (hv.equiv hv' e).to_linear_equiv = v.equiv v' e
rfl
lemma
orthonormal.equiv_to_linear_equiv
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "basis", "orthonormal" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
orthonormal.equiv_apply {ι' : Type*} {v : basis ι 𝕜 E} (hv : orthonormal 𝕜 v) {v' : basis ι' 𝕜 E'} (hv' : orthonormal 𝕜 v') (e : ι ≃ ι') (i : ι) : hv.equiv hv' e (v i) = v' (e i)
basis.equiv_apply _ _ _ _
lemma
orthonormal.equiv_apply
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "basis", "basis.equiv_apply", "orthonormal" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
orthonormal.equiv_refl {v : basis ι 𝕜 E} (hv : orthonormal 𝕜 v) : hv.equiv hv (equiv.refl ι) = linear_isometry_equiv.refl 𝕜 E
v.ext_linear_isometry_equiv $ λ i, by simp only [orthonormal.equiv_apply, equiv.coe_refl, id.def, linear_isometry_equiv.coe_refl]
lemma
orthonormal.equiv_refl
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "basis", "equiv.coe_refl", "equiv.refl", "linear_isometry_equiv.coe_refl", "linear_isometry_equiv.refl", "orthonormal", "orthonormal.equiv_apply" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
orthonormal.equiv_symm {v : basis ι 𝕜 E} (hv : orthonormal 𝕜 v) {v' : basis ι' 𝕜 E'} (hv' : orthonormal 𝕜 v') (e : ι ≃ ι') : (hv.equiv hv' e).symm = hv'.equiv hv e.symm
v'.ext_linear_isometry_equiv $ λ i, (hv.equiv hv' e).injective $ by simp only [linear_isometry_equiv.apply_symm_apply, orthonormal.equiv_apply, e.apply_symm_apply]
lemma
orthonormal.equiv_symm
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "basis", "linear_isometry_equiv.apply_symm_apply", "orthonormal", "orthonormal.equiv_apply" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
orthonormal.equiv_trans {v : basis ι 𝕜 E} (hv : orthonormal 𝕜 v) {v' : basis ι' 𝕜 E'} (hv' : orthonormal 𝕜 v') (e : ι ≃ ι') {v'' : basis ι'' 𝕜 E''} (hv'' : orthonormal 𝕜 v'') (e' : ι' ≃ ι'') : (hv.equiv hv' e).trans (hv'.equiv hv'' e') = hv.equiv hv'' (e.trans e')
v.ext_linear_isometry_equiv $ λ i, by simp only [linear_isometry_equiv.trans_apply, orthonormal.equiv_apply, e.coe_trans]
lemma
orthonormal.equiv_trans
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "basis", "linear_isometry_equiv.trans_apply", "orthonormal", "orthonormal.equiv_apply" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
orthonormal.map_equiv {v : basis ι 𝕜 E} (hv : orthonormal 𝕜 v) {v' : basis ι' 𝕜 E'} (hv' : orthonormal 𝕜 v') (e : ι ≃ ι') : v.map ((hv.equiv hv' e).to_linear_equiv) = v'.reindex e.symm
v.map_equiv _ _
lemma
orthonormal.map_equiv
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "basis", "orthonormal" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
real_inner_eq_norm_add_mul_self_sub_norm_mul_self_sub_norm_mul_self_div_two (x y : F) : ⟪x, y⟫_ℝ = (‖x + y‖ * ‖x + y‖ - ‖x‖ * ‖x‖ - ‖y‖ * ‖y‖) / 2
re_to_real.symm.trans $ re_inner_eq_norm_add_mul_self_sub_norm_mul_self_sub_norm_mul_self_div_two x y
lemma
real_inner_eq_norm_add_mul_self_sub_norm_mul_self_sub_norm_mul_self_div_two
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "re_inner_eq_norm_add_mul_self_sub_norm_mul_self_sub_norm_mul_self_div_two" ]
Polarization identity: The real inner product, in terms of the norm.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
real_inner_eq_norm_mul_self_add_norm_mul_self_sub_norm_sub_mul_self_div_two (x y : F) : ⟪x, y⟫_ℝ = (‖x‖ * ‖x‖ + ‖y‖ * ‖y‖ - ‖x - y‖ * ‖x - y‖) / 2
re_to_real.symm.trans $ re_inner_eq_norm_mul_self_add_norm_mul_self_sub_norm_sub_mul_self_div_two x y
lemma
real_inner_eq_norm_mul_self_add_norm_mul_self_sub_norm_sub_mul_self_div_two
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "re_inner_eq_norm_mul_self_add_norm_mul_self_sub_norm_sub_mul_self_div_two" ]
Polarization identity: The real inner product, in terms of the norm.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
norm_add_sq_eq_norm_sq_add_norm_sq_iff_real_inner_eq_zero (x y : F) : ‖x + y‖ * ‖x + y‖ = ‖x‖ * ‖x‖ + ‖y‖ * ‖y‖ ↔ ⟪x, y⟫_ℝ = 0
begin rw [@norm_add_mul_self ℝ, add_right_cancel_iff, add_right_eq_self, mul_eq_zero], norm_num end
lemma
norm_add_sq_eq_norm_sq_add_norm_sq_iff_real_inner_eq_zero
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "mul_eq_zero", "norm_add_mul_self" ]
Pythagorean theorem, if-and-only-if vector inner product form.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
norm_add_eq_sqrt_iff_real_inner_eq_zero {x y : F} : ‖x + y‖ = sqrt (‖x‖ * ‖x‖ + ‖y‖ * ‖y‖) ↔ ⟪x, y⟫_ℝ = 0
by rw [←norm_add_sq_eq_norm_sq_add_norm_sq_iff_real_inner_eq_zero, eq_comm, sqrt_eq_iff_mul_self_eq (add_nonneg (mul_self_nonneg _) (mul_self_nonneg _)) (norm_nonneg _)]
lemma
norm_add_eq_sqrt_iff_real_inner_eq_zero
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "mul_self_nonneg" ]
Pythagorean theorem, if-and-if vector inner product form using square roots.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
norm_add_sq_eq_norm_sq_add_norm_sq_of_inner_eq_zero (x y : E) (h : ⟪x, y⟫ = 0) : ‖x + y‖ * ‖x + y‖ = ‖x‖ * ‖x‖ + ‖y‖ * ‖y‖
begin rw [@norm_add_mul_self 𝕜, add_right_cancel_iff, add_right_eq_self, mul_eq_zero], apply or.inr, simp only [h, zero_re'], end
lemma
norm_add_sq_eq_norm_sq_add_norm_sq_of_inner_eq_zero
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "mul_eq_zero", "norm_add_mul_self" ]
Pythagorean theorem, vector inner product form.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
norm_add_sq_eq_norm_sq_add_norm_sq_real {x y : F} (h : ⟪x, y⟫_ℝ = 0) : ‖x + y‖ * ‖x + y‖ = ‖x‖ * ‖x‖ + ‖y‖ * ‖y‖
(norm_add_sq_eq_norm_sq_add_norm_sq_iff_real_inner_eq_zero x y).2 h
lemma
norm_add_sq_eq_norm_sq_add_norm_sq_real
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "norm_add_sq_eq_norm_sq_add_norm_sq_iff_real_inner_eq_zero" ]
Pythagorean theorem, vector inner product form.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
norm_sub_sq_eq_norm_sq_add_norm_sq_iff_real_inner_eq_zero (x y : F) : ‖x - y‖ * ‖x - y‖ = ‖x‖ * ‖x‖ + ‖y‖ * ‖y‖ ↔ ⟪x, y⟫_ℝ = 0
begin rw [@norm_sub_mul_self ℝ, add_right_cancel_iff, sub_eq_add_neg, add_right_eq_self, neg_eq_zero, mul_eq_zero], norm_num end
lemma
norm_sub_sq_eq_norm_sq_add_norm_sq_iff_real_inner_eq_zero
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "mul_eq_zero", "norm_sub_mul_self" ]
Pythagorean theorem, subtracting vectors, if-and-only-if vector inner product form.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
norm_sub_eq_sqrt_iff_real_inner_eq_zero {x y : F} : ‖x - y‖ = sqrt (‖x‖ * ‖x‖ + ‖y‖ * ‖y‖) ↔ ⟪x, y⟫_ℝ = 0
by rw [←norm_sub_sq_eq_norm_sq_add_norm_sq_iff_real_inner_eq_zero, eq_comm, sqrt_eq_iff_mul_self_eq (add_nonneg (mul_self_nonneg _) (mul_self_nonneg _)) (norm_nonneg _)]
lemma
norm_sub_eq_sqrt_iff_real_inner_eq_zero
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "mul_self_nonneg" ]
Pythagorean theorem, subtracting vectors, if-and-if vector inner product form using square roots.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
norm_sub_sq_eq_norm_sq_add_norm_sq_real {x y : F} (h : ⟪x, y⟫_ℝ = 0) : ‖x - y‖ * ‖x - y‖ = ‖x‖ * ‖x‖ + ‖y‖ * ‖y‖
(norm_sub_sq_eq_norm_sq_add_norm_sq_iff_real_inner_eq_zero x y).2 h
lemma
norm_sub_sq_eq_norm_sq_add_norm_sq_real
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "norm_sub_sq_eq_norm_sq_add_norm_sq_iff_real_inner_eq_zero" ]
Pythagorean theorem, subtracting vectors, vector inner product form.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
real_inner_add_sub_eq_zero_iff (x y : F) : ⟪x + y, x - y⟫_ℝ = 0 ↔ ‖x‖ = ‖y‖
begin conv_rhs { rw ←mul_self_inj_of_nonneg (norm_nonneg _) (norm_nonneg _) }, simp only [←@inner_self_eq_norm_mul_norm ℝ, inner_add_left, inner_sub_right, real_inner_comm y x, sub_eq_zero, re_to_real], split, { intro h, rw [add_comm] at h, linarith }, { intro h, linarith } end
lemma
real_inner_add_sub_eq_zero_iff
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "inner_add_left", "inner_self_eq_norm_mul_norm", "inner_sub_right", "real_inner_comm" ]
The sum and difference of two vectors are orthogonal if and only if they have the same norm.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
norm_sub_eq_norm_add {v w : E} (h : ⟪v, w⟫ = 0) : ‖w - v‖ = ‖w + v‖
begin rw ←mul_self_inj_of_nonneg (norm_nonneg _) (norm_nonneg _), simp only [h, ←@inner_self_eq_norm_mul_norm 𝕜, sub_neg_eq_add, sub_zero, map_sub, zero_re', zero_sub, add_zero, map_add, inner_add_right, inner_sub_left, inner_sub_right, inner_re_symm, zero_add] end
lemma
norm_sub_eq_norm_add
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "inner_add_right", "inner_re_symm", "inner_self_eq_norm_mul_norm", "inner_sub_left", "inner_sub_right" ]
Given two orthogonal vectors, their sum and difference have equal norms.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
abs_real_inner_div_norm_mul_norm_le_one (x y : F) : |⟪x, y⟫_ℝ / (‖x‖ * ‖y‖)| ≤ 1
begin rw [abs_div, abs_mul, abs_norm, abs_norm], exact div_le_one_of_le (abs_real_inner_le_norm x y) (by positivity) end
lemma
abs_real_inner_div_norm_mul_norm_le_one
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "abs_div", "abs_mul", "abs_norm", "abs_real_inner_le_norm", "div_le_one_of_le" ]
The real inner product of two vectors, divided by the product of their norms, has absolute value at most 1.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
real_inner_smul_self_left (x : F) (r : ℝ) : ⟪r • x, x⟫_ℝ = r * (‖x‖ * ‖x‖)
by rw [real_inner_smul_left, ←real_inner_self_eq_norm_mul_norm]
lemma
real_inner_smul_self_left
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "real_inner_smul_left" ]
The inner product of a vector with a multiple of itself.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
real_inner_smul_self_right (x : F) (r : ℝ) : ⟪x, r • x⟫_ℝ = r * (‖x‖ * ‖x‖)
by rw [inner_smul_right, ←real_inner_self_eq_norm_mul_norm]
lemma
real_inner_smul_self_right
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "inner_smul_right" ]
The inner product of a vector with a multiple of itself.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
norm_inner_div_norm_mul_norm_eq_one_of_ne_zero_of_ne_zero_mul {x : E} {r : 𝕜} (hx : x ≠ 0) (hr : r ≠ 0) : ‖⟪x, r • x⟫‖ / (‖x‖ * ‖r • x‖) = 1
begin have hx' : ‖x‖ ≠ 0 := by simp [hx], have hr' : ‖r‖ ≠ 0 := by simp [hr], rw [inner_smul_right, norm_mul, ← inner_self_re_eq_norm, inner_self_eq_norm_mul_norm, norm_smul], rw [← mul_assoc, ← div_div, mul_div_cancel _ hx', ← div_div, mul_comm, mul_div_cancel _ hr', div_self hx'], end
lemma
norm_inner_div_norm_mul_norm_eq_one_of_ne_zero_of_ne_zero_mul
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "div_div", "div_self", "inner_self_eq_norm_mul_norm", "inner_self_re_eq_norm", "inner_smul_right", "mul_assoc", "mul_comm", "mul_div_cancel", "norm_mul", "norm_smul" ]
The inner product of a nonzero vector with a nonzero multiple of itself, divided by the product of their norms, has absolute value 1.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
abs_real_inner_div_norm_mul_norm_eq_one_of_ne_zero_of_ne_zero_mul {x : F} {r : ℝ} (hx : x ≠ 0) (hr : r ≠ 0) : |⟪x, r • x⟫_ℝ| / (‖x‖ * ‖r • x‖) = 1
norm_inner_div_norm_mul_norm_eq_one_of_ne_zero_of_ne_zero_mul hx hr
lemma
abs_real_inner_div_norm_mul_norm_eq_one_of_ne_zero_of_ne_zero_mul
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "norm_inner_div_norm_mul_norm_eq_one_of_ne_zero_of_ne_zero_mul" ]
The inner product of a nonzero vector with a nonzero multiple of itself, divided by the product of their norms, has absolute value 1.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
real_inner_div_norm_mul_norm_eq_one_of_ne_zero_of_pos_mul {x : F} {r : ℝ} (hx : x ≠ 0) (hr : 0 < r) : ⟪x, r • x⟫_ℝ / (‖x‖ * ‖r • x‖) = 1
begin rw [real_inner_smul_self_right, norm_smul, real.norm_eq_abs, ←mul_assoc ‖x‖, mul_comm _ (|r|), mul_assoc, abs_of_nonneg hr.le, div_self], exact mul_ne_zero hr.ne' (mul_self_ne_zero.2 (norm_ne_zero_iff.2 hx)) end
lemma
real_inner_div_norm_mul_norm_eq_one_of_ne_zero_of_pos_mul
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "abs_of_nonneg", "div_self", "mul_assoc", "mul_comm", "mul_ne_zero", "norm_smul", "real.norm_eq_abs", "real_inner_smul_self_right" ]
The inner product of a nonzero vector with a positive multiple of itself, divided by the product of their norms, has value 1.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
real_inner_div_norm_mul_norm_eq_neg_one_of_ne_zero_of_neg_mul {x : F} {r : ℝ} (hx : x ≠ 0) (hr : r < 0) : ⟪x, r • x⟫_ℝ / (‖x‖ * ‖r • x‖) = -1
begin rw [real_inner_smul_self_right, norm_smul, real.norm_eq_abs, ←mul_assoc ‖x‖, mul_comm _ (|r|), mul_assoc, abs_of_neg hr, neg_mul, div_neg_eq_neg_div, div_self], exact mul_ne_zero hr.ne (mul_self_ne_zero.2 (norm_ne_zero_iff.2 hx)) end
lemma
real_inner_div_norm_mul_norm_eq_neg_one_of_ne_zero_of_neg_mul
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "abs_of_neg", "div_neg_eq_neg_div", "div_self", "mul_assoc", "mul_comm", "mul_ne_zero", "neg_mul", "norm_smul", "real.norm_eq_abs", "real_inner_smul_self_right" ]
The inner product of a nonzero vector with a negative multiple of itself, divided by the product of their norms, has value -1.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
norm_inner_eq_norm_tfae (x y : E) : tfae [‖⟪x, y⟫‖ = ‖x‖ * ‖y‖, x = 0 ∨ y = (⟪x, y⟫ / ⟪x, x⟫) • x, x = 0 ∨ ∃ r : 𝕜, y = r • x, x = 0 ∨ y ∈ 𝕜 ∙ x]
begin tfae_have : 1 → 2, { refine λ h, or_iff_not_imp_left.2 (λ hx₀, _), have : ‖x‖ ^ 2 ≠ 0 := pow_ne_zero _ (norm_ne_zero_iff.2 hx₀), rw [← sq_eq_sq (norm_nonneg _) (mul_nonneg (norm_nonneg _) (norm_nonneg _)), mul_pow, ← mul_right_inj' this, eq_comm, ← sub_eq_zero, ← mul_sub] at h, simp only [@n...
lemma
norm_inner_eq_norm_tfae
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "div_eq_inv_mul", "inner_product_space.core", "inner_product_space.core.cauchy_schwarz_aux", "inner_product_space.core.norm_sq_eq_zero", "inner_product_space.to_core", "inner_self_eq_norm_mul_norm", "inner_self_eq_norm_sq_to_K", "inner_self_ne_zero", "inner_smul_right", "inv_smul_smul₀", "mul_le...
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
norm_inner_eq_norm_iff {x y : E} (hx₀ : x ≠ 0) (hy₀ : y ≠ 0) : ‖⟪x, y⟫‖ = ‖x‖ * ‖y‖ ↔ ∃ (r : 𝕜), r ≠ 0 ∧ y = r • x
calc ‖⟪x, y⟫‖ = ‖x‖ * ‖y‖ ↔ x = 0 ∨ ∃ r : 𝕜, y = r • x : (@norm_inner_eq_norm_tfae 𝕜 _ _ _ _ x y).out 0 2 ... ↔ ∃ r : 𝕜, y = r • x : or_iff_right hx₀ ... ↔ ∃ r : 𝕜, r ≠ 0 ∧ y = r • x : ⟨λ ⟨r, h⟩, ⟨r, λ hr₀, hy₀ $ h.symm ▸ smul_eq_zero.2 $ or.inl hr₀, h⟩, λ ⟨r, hr₀, h⟩, ⟨r, h⟩⟩
lemma
norm_inner_eq_norm_iff
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "norm_inner_eq_norm_tfae", "or_iff_right" ]
If the inner product of two vectors is equal to the product of their norms, then the two vectors are multiples of each other. One form of the equality case for Cauchy-Schwarz. Compare `inner_eq_norm_mul_iff`, which takes the stronger hypothesis `⟪x, y⟫ = ‖x‖ * ‖y‖`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
norm_inner_div_norm_mul_norm_eq_one_iff (x y : E) : ‖(⟪x, y⟫ / (‖x‖ * ‖y‖))‖ = 1 ↔ (x ≠ 0 ∧ ∃ (r : 𝕜), r ≠ 0 ∧ y = r • x)
begin split, { intro h, have hx₀ : x ≠ 0 := λ h₀, by simpa [h₀] using h, have hy₀ : y ≠ 0 := λ h₀, by simpa [h₀] using h, refine ⟨hx₀, (norm_inner_eq_norm_iff hx₀ hy₀).1 $ eq_of_div_eq_one _⟩, simpa using h }, { rintro ⟨hx, ⟨r, ⟨hr, rfl⟩⟩⟩, simp only [norm_div, norm_mul, norm_of_real, abs_norm...
lemma
norm_inner_div_norm_mul_norm_eq_one_iff
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "abs_norm", "eq_of_div_eq_one", "norm_div", "norm_inner_div_norm_mul_norm_eq_one_of_ne_zero_of_ne_zero_mul", "norm_inner_eq_norm_iff", "norm_mul" ]
The inner product of two vectors, divided by the product of their norms, has absolute value 1 if and only if they are nonzero and one is a multiple of the other. One form of equality case for Cauchy-Schwarz.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
abs_real_inner_div_norm_mul_norm_eq_one_iff (x y : F) :
|⟪x, y⟫_ℝ / (‖x‖ * ‖y‖)| = 1 ↔ (x ≠ 0 ∧ ∃ (r : ℝ), r ≠ 0 ∧ y = r • x) := @norm_inner_div_norm_mul_norm_eq_one_iff ℝ F _ _ _ x y
lemma
abs_real_inner_div_norm_mul_norm_eq_one_iff
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "norm_inner_div_norm_mul_norm_eq_one_iff" ]
The inner product of two vectors, divided by the product of their norms, has absolute value 1 if and only if they are nonzero and one is a multiple of the other. One form of equality case for Cauchy-Schwarz.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
inner_eq_norm_mul_iff_div {x y : E} (h₀ : x ≠ 0) : ⟪x, y⟫ = (‖x‖ : 𝕜) * ‖y‖ ↔ (‖y‖ / ‖x‖ : 𝕜) • x = y
begin have h₀' := h₀, rw [← norm_ne_zero_iff, ne.def, ← @of_real_eq_zero 𝕜] at h₀', split; intro h, { have : x = 0 ∨ y = (⟪x, y⟫ / ⟪x, x⟫ : 𝕜) • x := ((@norm_inner_eq_norm_tfae 𝕜 _ _ _ _ x y).out 0 1).1 (by simp [h]), rw [this.resolve_left h₀, h], simp [norm_smul, inner_self_norm_to_K, h₀'] }, ...
lemma
inner_eq_norm_mul_iff_div
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "inner_self_eq_norm_sq_to_K", "inner_self_norm_to_K", "inner_smul_right", "mul_left_comm", "norm_inner_eq_norm_tfae", "norm_smul" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
inner_eq_norm_mul_iff {x y : E} : ⟪x, y⟫ = (‖x‖ : 𝕜) * ‖y‖ ↔ (‖y‖ : 𝕜) • x = (‖x‖ : 𝕜) • y
begin rcases eq_or_ne x 0 with (rfl | h₀), { simp }, { rw [inner_eq_norm_mul_iff_div h₀, div_eq_inv_mul, mul_smul, inv_smul_eq_iff₀], rwa [ne.def, of_real_eq_zero, norm_eq_zero] }, end
lemma
inner_eq_norm_mul_iff
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "div_eq_inv_mul", "eq_or_ne", "inner_eq_norm_mul_iff_div", "inv_smul_eq_iff₀", "norm_eq_zero" ]
If the inner product of two vectors is equal to the product of their norms (i.e., `⟪x, y⟫ = ‖x‖ * ‖y‖`), then the two vectors are nonnegative real multiples of each other. One form of the equality case for Cauchy-Schwarz. Compare `norm_inner_eq_norm_iff`, which takes the weaker hypothesis `abs ⟪x, y⟫ = ‖x‖ * ‖y‖`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
inner_eq_norm_mul_iff_real {x y : F} : ⟪x, y⟫_ℝ = ‖x‖ * ‖y‖ ↔ ‖y‖ • x = ‖x‖ • y
inner_eq_norm_mul_iff
lemma
inner_eq_norm_mul_iff_real
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "inner_eq_norm_mul_iff" ]
If the inner product of two vectors is equal to the product of their norms (i.e., `⟪x, y⟫ = ‖x‖ * ‖y‖`), then the two vectors are nonnegative real multiples of each other. One form of the equality case for Cauchy-Schwarz. Compare `norm_inner_eq_norm_iff`, which takes the weaker hypothesis `abs ⟪x, y⟫ = ‖x‖ * ‖y‖`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
real_inner_div_norm_mul_norm_eq_one_iff (x y : F) : ⟪x, y⟫_ℝ / (‖x‖ * ‖y‖) = 1 ↔ (x ≠ 0 ∧ ∃ (r : ℝ), 0 < r ∧ y = r • x)
begin split, { intro h, have hx₀ : x ≠ 0 := λ h₀, by simpa [h₀] using h, have hy₀ : y ≠ 0 := λ h₀, by simpa [h₀] using h, refine ⟨hx₀, ‖y‖ / ‖x‖, div_pos (norm_pos_iff.2 hy₀) (norm_pos_iff.2 hx₀), _⟩, exact ((inner_eq_norm_mul_iff_div hx₀).1 (eq_of_div_eq_one h)).symm }, { rintro ⟨hx, ⟨r, ⟨hr, rfl...
lemma
real_inner_div_norm_mul_norm_eq_one_iff
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "div_pos", "eq_of_div_eq_one", "inner_eq_norm_mul_iff_div", "real_inner_div_norm_mul_norm_eq_one_of_ne_zero_of_pos_mul" ]
The inner product of two vectors, divided by the product of their norms, has value 1 if and only if they are nonzero and one is a positive multiple of the other.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
real_inner_div_norm_mul_norm_eq_neg_one_iff (x y : F) : ⟪x, y⟫_ℝ / (‖x‖ * ‖y‖) = -1 ↔ (x ≠ 0 ∧ ∃ (r : ℝ), r < 0 ∧ y = r • x)
begin rw [← neg_eq_iff_eq_neg, ← neg_div, ← inner_neg_right, ← norm_neg y, real_inner_div_norm_mul_norm_eq_one_iff, (@neg_surjective ℝ _).exists], refine iff.rfl.and (exists_congr $ λ r, _), rw [neg_pos, neg_smul, neg_inj] end
lemma
real_inner_div_norm_mul_norm_eq_neg_one_iff
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "inner_neg_right", "neg_div", "neg_smul", "real_inner_div_norm_mul_norm_eq_one_iff" ]
The inner product of two vectors, divided by the product of their norms, has value -1 if and only if they are nonzero and one is a negative multiple of the other.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
inner_eq_one_iff_of_norm_one {x y : E} (hx : ‖x‖ = 1) (hy : ‖y‖ = 1) : ⟪x, y⟫ = 1 ↔ x = y
by { convert inner_eq_norm_mul_iff using 2; simp [hx, hy] }
lemma
inner_eq_one_iff_of_norm_one
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "inner_eq_norm_mul_iff" ]
If the inner product of two unit vectors is `1`, then the two vectors are equal. One form of the equality case for Cauchy-Schwarz.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
inner_lt_norm_mul_iff_real {x y : F} : ⟪x, y⟫_ℝ < ‖x‖ * ‖y‖ ↔ ‖y‖ • x ≠ ‖x‖ • y
calc ⟪x, y⟫_ℝ < ‖x‖ * ‖y‖ ↔ ⟪x, y⟫_ℝ ≠ ‖x‖ * ‖y‖ : ⟨ne_of_lt, lt_of_le_of_ne (real_inner_le_norm _ _)⟩ ... ↔ ‖y‖ • x ≠ ‖x‖ • y : not_congr inner_eq_norm_mul_iff_real
lemma
inner_lt_norm_mul_iff_real
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "inner_eq_norm_mul_iff_real", "real_inner_le_norm" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
inner_lt_one_iff_real_of_norm_one {x y : F} (hx : ‖x‖ = 1) (hy : ‖y‖ = 1) : ⟪x, y⟫_ℝ < 1 ↔ x ≠ y
by { convert inner_lt_norm_mul_iff_real; simp [hx, hy] }
lemma
inner_lt_one_iff_real_of_norm_one
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "inner_lt_norm_mul_iff_real" ]
If the inner product of two unit vectors is strictly less than `1`, then the two vectors are distinct. One form of the equality case for Cauchy-Schwarz.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
inner_sum_smul_sum_smul_of_sum_eq_zero {ι₁ : Type*} {s₁ : finset ι₁} {w₁ : ι₁ → ℝ} (v₁ : ι₁ → F) (h₁ : ∑ i in s₁, w₁ i = 0) {ι₂ : Type*} {s₂ : finset ι₂} {w₂ : ι₂ → ℝ} (v₂ : ι₂ → F) (h₂ : ∑ i in s₂, w₂ i = 0) : ⟪(∑ i₁ in s₁, w₁ i₁ • v₁ i₁), (∑ i₂ in s₂, w₂ i₂ • v₂ i₂)⟫_ℝ = (-∑ i₁ in s₁, ∑ i₂ in s₂, w₁ i₁ ...
by simp_rw [sum_inner, inner_sum, real_inner_smul_left, real_inner_smul_right, real_inner_eq_norm_mul_self_add_norm_mul_self_sub_norm_sub_mul_self_div_two, ←div_sub_div_same, ←div_add_div_same, mul_sub_left_distrib, left_distrib, finset.sum_sub_distrib, finset.sum_add_distrib, ←finse...
lemma
inner_sum_smul_sum_smul_of_sum_eq_zero
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "finset", "finset.mul_sum", "finset.sum_div", "inner_sum", "left_distrib", "mul_assoc", "mul_div_assoc", "mul_sub_left_distrib", "mul_zero", "neg_div", "real_inner_eq_norm_mul_self_add_norm_mul_self_sub_norm_sub_mul_self_div_two", "real_inner_smul_left", "real_inner_smul_right", "sum_inner...
The inner product of two weighted sums, where the weights in each sum add to 0, in terms of the norms of pairwise differences.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
innerₛₗ : E →ₗ⋆[𝕜] E →ₗ[𝕜] 𝕜
linear_map.mk₂'ₛₗ _ _ (λ v w, ⟪v, w⟫) inner_add_left (λ _ _ _, inner_smul_left _ _ _) inner_add_right (λ _ _ _, inner_smul_right _ _ _)
def
innerₛₗ
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "inner_add_left", "inner_add_right", "inner_smul_left", "inner_smul_right", "linear_map.mk₂'ₛₗ" ]
The inner product as a sesquilinear map.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
innerₛₗ_apply_coe (v : E) : ⇑(innerₛₗ 𝕜 v) = λ w, ⟪v, w⟫
rfl
lemma
innerₛₗ_apply_coe
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "innerₛₗ" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
innerₛₗ_apply (v w : E) : innerₛₗ 𝕜 v w = ⟪v, w⟫
rfl
lemma
innerₛₗ_apply
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "innerₛₗ" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
innerSL : E →L⋆[𝕜] E →L[𝕜] 𝕜
linear_map.mk_continuous₂ (innerₛₗ 𝕜) 1 (λ x y, by simp only [norm_inner_le_norm, one_mul, innerₛₗ_apply])
def
innerSL
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "innerₛₗ", "innerₛₗ_apply", "linear_map.mk_continuous₂", "norm_inner_le_norm", "one_mul" ]
The inner product as a continuous sesquilinear map. Note that `to_dual_map` (resp. `to_dual`) in `inner_product_space.dual` is a version of this given as a linear isometry (resp. linear isometric equivalence).
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
innerSL_apply_coe (v : E) : ⇑(innerSL 𝕜 v) = λ w, ⟪v, w⟫
rfl
lemma
innerSL_apply_coe
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "innerSL" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
innerSL_apply (v w : E) : innerSL 𝕜 v w = ⟪v, w⟫
rfl
lemma
innerSL_apply
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "innerSL" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
innerSL_apply_norm (x : E) : ‖innerSL 𝕜 x‖ = ‖x‖
begin refine le_antisymm ((innerSL 𝕜 x).op_norm_le_bound (norm_nonneg _) (λ y, norm_inner_le_norm _ _)) _, rcases eq_or_ne x 0 with (rfl | h), { simp }, { refine (mul_le_mul_right (norm_pos_iff.2 h)).mp _, calc ‖x‖ * ‖x‖ = ‖(⟪x, x⟫ : 𝕜)‖ : by rw [← sq, inner_self_eq_norm_sq_to_K, norm_pow, norm_...
lemma
innerSL_apply_norm
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "abs_norm", "eq_or_ne", "innerSL", "inner_self_eq_norm_sq_to_K", "mul_le_mul_right", "norm_inner_le_norm", "norm_pow" ]
`innerSL` is an isometry. Note that the associated `linear_isometry` is defined in `inner_product_space.dual` as `to_dual_map`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
innerSL_flip : E →L[𝕜] E →L⋆[𝕜] 𝕜
@continuous_linear_map.flipₗᵢ' 𝕜 𝕜 𝕜 E E 𝕜 _ _ _ _ _ _ _ _ _ (ring_hom.id 𝕜) (star_ring_end 𝕜) _ _ (innerSL 𝕜)
def
innerSL_flip
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "continuous_linear_map.flipₗᵢ'", "innerSL", "ring_hom.id", "star_ring_end" ]
The inner product as a continuous sesquilinear map, with the two arguments flipped.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
innerSL_flip_apply (x y : E) : innerSL_flip 𝕜 x y = ⟪y, x⟫
rfl
lemma
innerSL_flip_apply
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "innerSL_flip" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
to_sesq_form : (E →L[𝕜] E') →L[𝕜] E' →L⋆[𝕜] E →L[𝕜] 𝕜
↑((continuous_linear_map.flipₗᵢ' E E' 𝕜 (star_ring_end 𝕜) (ring_hom.id 𝕜)).to_continuous_linear_equiv) ∘L (continuous_linear_map.compSL E E' (E' →L⋆[𝕜] 𝕜) (ring_hom.id 𝕜) (ring_hom.id 𝕜) (innerSL_flip 𝕜))
def
continuous_linear_map.to_sesq_form
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "continuous_linear_map.compSL", "continuous_linear_map.flipₗᵢ'", "innerSL_flip", "ring_hom.id", "star_ring_end" ]
Given `f : E →L[𝕜] E'`, construct the continuous sesquilinear form `λ x y, ⟪x, A y⟫`, given as a continuous linear map.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
to_sesq_form_apply_coe (f : E →L[𝕜] E') (x : E') : to_sesq_form f x = (innerSL 𝕜 x).comp f
rfl
lemma
continuous_linear_map.to_sesq_form_apply_coe
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "innerSL" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
to_sesq_form_apply_norm_le {f : E →L[𝕜] E'} {v : E'} : ‖to_sesq_form f v‖ ≤ ‖f‖ * ‖v‖
begin refine op_norm_le_bound _ (mul_nonneg (norm_nonneg _) (norm_nonneg _)) _, intro x, have h₁ : ‖f x‖ ≤ ‖f‖ * ‖x‖ := le_op_norm _ _, have h₂ := @norm_inner_le_norm 𝕜 E' _ _ _ v (f x), calc ‖⟪v, f x⟫‖ ≤ ‖v‖ * ‖f x‖ : h₂ ... ≤ ‖v‖ * (‖f‖ * ‖x‖) : mul_le_mul_of_nonneg_left h₁ (norm_nonn...
lemma
continuous_linear_map.to_sesq_form_apply_norm_le
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "mul_le_mul_of_nonneg_left", "norm_inner_le_norm", "ring" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_bounded_bilinear_map_inner [normed_space ℝ E] : is_bounded_bilinear_map ℝ (λ p : E × E, ⟪p.1, p.2⟫)
{ add_left := inner_add_left, smul_left := λ r x y, by simp only [← algebra_map_smul 𝕜 r x, algebra_map_eq_of_real, inner_smul_real_left], add_right := inner_add_right, smul_right := λ r x y, by simp only [← algebra_map_smul 𝕜 r y, algebra_map_eq_of_real, inner_smul_real_right], bound := ⟨1, zero_lt_o...
lemma
is_bounded_bilinear_map_inner
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "algebra_map_smul", "bound", "inner_add_left", "inner_add_right", "inner_smul_real_left", "inner_smul_real_right", "is_bounded_bilinear_map", "norm_inner_le_norm", "normed_space", "one_mul", "zero_lt_one" ]
When an inner product space `E` over `𝕜` is considered as a real normed space, its inner product satisfies `is_bounded_bilinear_map`. In order to state these results, we need a `normed_space ℝ E` instance. We will later establish such an instance by restriction-of-scalars, `inner_product_space.is_R_or_C_to_real 𝕜 E`...
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
orthonormal.sum_inner_products_le {s : finset ι} (hv : orthonormal 𝕜 v) : ∑ i in s, ‖⟪v i, x⟫‖ ^ 2 ≤ ‖x‖ ^ 2
begin have h₂ : ∑ i in s, ∑ j in s, ⟪v i, x⟫ * ⟪x, v j⟫ * ⟪v j, v i⟫ = (∑ k in s, (⟪v k, x⟫ * ⟪x, v k⟫) : 𝕜), { exact hv.inner_left_right_finset }, have h₃ : ∀ z : 𝕜, re (z * conj (z)) = ‖z‖ ^ 2, { intro z, simp only [mul_conj, norm_sq_eq_def'], norm_cast, }, suffices hbf: ‖x - ∑ i in s, ⟪v i, ...
lemma
orthonormal.sum_inner_products_le
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "finset", "finset.mul_sum", "inner_conj_symm", "inner_smul_left", "inner_smul_right", "inner_sum", "norm_sub_sq", "orthonormal", "pow_nonneg", "sum_inner", "two_mul" ]
Bessel's inequality for finite sums.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
orthonormal.tsum_inner_products_le (hv : orthonormal 𝕜 v) : ∑' i, ‖⟪v i, x⟫‖ ^ 2 ≤ ‖x‖ ^ 2
begin refine tsum_le_of_sum_le' _ (λ s, hv.sum_inner_products_le x), simp only [norm_nonneg, pow_nonneg] end
lemma
orthonormal.tsum_inner_products_le
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "orthonormal", "pow_nonneg", "tsum_le_of_sum_le'" ]
Bessel's inequality.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
orthonormal.inner_products_summable (hv : orthonormal 𝕜 v) : summable (λ i, ‖⟪v i, x⟫‖ ^ 2)
begin use ⨆ s : finset ι, ∑ i in s, ‖⟪v i, x⟫‖ ^ 2, apply has_sum_of_is_lub_of_nonneg, { intro b, simp only [norm_nonneg, pow_nonneg], }, { refine is_lub_csupr _, use ‖x‖ ^ 2, rintro y ⟨s, rfl⟩, exact hv.sum_inner_products_le x } end
lemma
orthonormal.inner_products_summable
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "finset", "has_sum_of_is_lub_of_nonneg", "is_lub_csupr", "orthonormal", "pow_nonneg", "summable" ]
The sum defined in Bessel's inequality is summable.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_R_or_C.inner_product_space : inner_product_space 𝕜 𝕜
{ inner := λ x y, conj x * y, norm_sq_eq_inner := λ x, by { unfold inner, rw [mul_comm, mul_conj, of_real_re, norm_sq_eq_def'] }, conj_symm := λ x y, by simp only [mul_comm, map_mul, star_ring_end_self_apply], add_left := λ x y z, by simp only [add_mul, map_add], smul_left := λ x y z, by simp only [mul_asso...
instance
is_R_or_C.inner_product_space
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "inner_product_space", "map_mul", "mul_assoc", "mul_comm", "smul_eq_mul", "star_ring_end_self_apply" ]
A field `𝕜` satisfying `is_R_or_C` is itself a `𝕜`-inner product space.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_R_or_C.inner_apply (x y : 𝕜) : ⟪x, y⟫ = (conj x) * y
rfl
lemma
is_R_or_C.inner_apply
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
submodule.inner_product_space (W : submodule 𝕜 E) : inner_product_space 𝕜 W
{ inner := λ x y, ⟪(x:E), (y:E)⟫, conj_symm := λ _ _, inner_conj_symm _ _, norm_sq_eq_inner := λ x, norm_sq_eq_inner (x : E), add_left := λ _ _ _, inner_add_left _ _ _, smul_left := λ _ _ _, inner_smul_left _ _ _, ..submodule.normed_space W }
instance
submodule.inner_product_space
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "inner_add_left", "inner_conj_symm", "inner_product_space", "inner_smul_left", "submodule", "submodule.normed_space" ]
Induced inner product on a submodule.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
submodule.coe_inner (W : submodule 𝕜 E) (x y : W) : ⟪x, y⟫ = ⟪(x:E), ↑y⟫
rfl
lemma
submodule.coe_inner
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "submodule" ]
The inner product on submodules is the same as on the ambient space.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
orthonormal.cod_restrict {ι : Type*} {v : ι → E} (hv : orthonormal 𝕜 v) (s : submodule 𝕜 E) (hvs : ∀ i, v i ∈ s) : @orthonormal 𝕜 s _ _ _ ι (set.cod_restrict v s hvs)
s.subtypeₗᵢ.orthonormal_comp_iff.mp hv
lemma
orthonormal.cod_restrict
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "orthonormal", "set.cod_restrict", "submodule" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
orthonormal_span {ι : Type*} {v : ι → E} (hv : orthonormal 𝕜 v) : @orthonormal 𝕜 (submodule.span 𝕜 (set.range v)) _ _ _ ι (λ i : ι, ⟨v i, submodule.subset_span (set.mem_range_self i)⟩)
hv.cod_restrict (submodule.span 𝕜 (set.range v)) (λ i, submodule.subset_span (set.mem_range_self i))
lemma
orthonormal_span
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "orthonormal", "set.mem_range_self", "set.range", "submodule.span", "submodule.subset_span" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
orthogonal_family (G : ι → Type*) [Π i, normed_add_comm_group (G i)] [Π i, inner_product_space 𝕜 (G i)] (V : Π i, G i →ₗᵢ[𝕜] E) : Prop
∀ ⦃i j⦄, i ≠ j → ∀ v : G i, ∀ w : G j, ⟪V i v, V j w⟫ = 0
def
orthogonal_family
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "inner_product_space", "normed_add_comm_group" ]
An indexed family of mutually-orthogonal subspaces of an inner product space `E`. The simple way to express this concept would be as a condition on `V : ι → submodule 𝕜 E`. We We instead implement it as a condition on a family of inner product spaces each equipped with an isometric embedding into `E`, thus making it...
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
orthonormal.orthogonal_family {v : ι → E} (hv : orthonormal 𝕜 v) : orthogonal_family 𝕜 (λ i : ι, 𝕜) (λ i, linear_isometry.to_span_singleton 𝕜 E (hv.1 i))
λ i j hij a b, by simp [inner_smul_left, inner_smul_right, hv.2 hij]
lemma
orthonormal.orthogonal_family
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "inner_smul_left", "inner_smul_right", "linear_isometry.to_span_singleton", "orthogonal_family", "orthonormal" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
orthogonal_family.eq_ite {i j : ι} (v : G i) (w : G j) : ⟪V i v, V j w⟫ = ite (i = j) ⟪V i v, V j w⟫ 0
begin split_ifs, { refl }, { exact hV h v w } end
lemma
orthogonal_family.eq_ite
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
orthogonal_family.inner_right_dfinsupp (l : ⨁ i, G i) (i : ι) (v : G i) : ⟪V i v, l.sum (λ j, V j)⟫ = ⟪v, l i⟫
calc ⟪V i v, l.sum (λ j, V j)⟫ = l.sum (λ j, λ w, ⟪V i v, V j w⟫) : dfinsupp.inner_sum (λ j, V j) l (V i v) ... = l.sum (λ j, λ w, ite (i=j) ⟪V i v, V j w⟫ 0) : congr_arg l.sum $ funext $ λ j, funext $ hV.eq_ite v ... = ⟪v, l i⟫ : begin simp only [dfinsupp.sum, submodule.coe_inner, finset.sum_ite_eq, ite_eq_lef...
lemma
orthogonal_family.inner_right_dfinsupp
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "dfinsupp.inner_sum", "dfinsupp.mem_support_to_fun", "inner_zero_right", "ite_eq_left_iff", "linear_isometry.inner_map_map", "of_not_not", "submodule.coe_inner" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
orthogonal_family.inner_right_fintype [fintype ι] (l : Π i, G i) (i : ι) (v : G i) : ⟪V i v, ∑ j : ι, V j (l j)⟫ = ⟪v, l i⟫
by classical; calc ⟪V i v, ∑ j : ι, V j (l j)⟫ = ∑ j : ι, ⟪V i v, V j (l j)⟫: by rw inner_sum ... = ∑ j, ite (i = j) ⟪V i v, V j (l j)⟫ 0 : congr_arg (finset.sum finset.univ) $ funext $ λ j, (hV.eq_ite v (l j)) ... = ⟪v, l i⟫ : by simp only [finset.sum_ite_eq, finset.mem_univ, (V i).inner_map_map, if_true]
lemma
orthogonal_family.inner_right_fintype
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "finset.mem_univ", "finset.univ", "fintype", "inner_sum" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
orthogonal_family.inner_sum (l₁ l₂ : Π i, G i) (s : finset ι) : ⟪∑ i in s, V i (l₁ i), ∑ j in s, V j (l₂ j)⟫ = ∑ i in s, ⟪l₁ i, l₂ i⟫
by classical; calc ⟪∑ i in s, V i (l₁ i), ∑ j in s, V j (l₂ j)⟫ = ∑ j in s, ∑ i in s, ⟪V i (l₁ i), V j (l₂ j)⟫ : by simp only [sum_inner, inner_sum] ... = ∑ j in s, ∑ i in s, ite (i = j) ⟪V i (l₁ i), V j (l₂ j)⟫ 0 : begin congr' with i, congr' with j, apply hV.eq_ite, end ... = ∑ i in s, ⟪l₁ i, l₂ i⟫ : by sim...
lemma
orthogonal_family.inner_sum
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "finset", "imp_self", "inner_sum", "linear_isometry.inner_map_map", "sum_inner" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
orthogonal_family.norm_sum (l : Π i, G i) (s : finset ι) : ‖∑ i in s, V i (l i)‖ ^ 2 = ∑ i in s, ‖l i‖ ^ 2
begin have : (‖∑ i in s, V i (l i)‖ ^ 2 : 𝕜) = ∑ i in s, ‖l i‖ ^ 2, { simp only [← inner_self_eq_norm_sq_to_K, hV.inner_sum] }, exact_mod_cast this, end
lemma
orthogonal_family.norm_sum
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "finset", "inner_self_eq_norm_sq_to_K" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
orthogonal_family.comp {γ : Type*} {f : γ → ι} (hf : function.injective f) : orthogonal_family 𝕜 (λ g, G (f g)) (λ g, V (f g))
λ i j hij v w, hV (hf.ne hij) v w
lemma
orthogonal_family.comp
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "orthogonal_family" ]
The composition of an orthogonal family of subspaces with an injective function is also an orthogonal family.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
orthogonal_family.orthonormal_sigma_orthonormal {α : ι → Type*} {v_family : Π i, (α i) → G i} (hv_family : ∀ i, orthonormal 𝕜 (v_family i)) : orthonormal 𝕜 (λ a : Σ i, α i, V a.1 (v_family a.1 a.2))
begin split, { rintros ⟨i, v⟩, simpa only [linear_isometry.norm_map] using (hv_family i).left v }, rintros ⟨i, v⟩ ⟨j, w⟩ hvw, by_cases hij : i = j, { subst hij, have : v ≠ w := λ h, by { subst h, exact hvw rfl }, simpa only [linear_isometry.inner_map_map] using (hv_family i).2 this }, { exact hV...
lemma
orthogonal_family.orthonormal_sigma_orthonormal
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "linear_isometry.inner_map_map", "linear_isometry.norm_map", "orthonormal" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
orthogonal_family.norm_sq_diff_sum (f : Π i, G i) (s₁ s₂ : finset ι) : ‖∑ i in s₁, V i (f i) - ∑ i in s₂, V i (f i)‖ ^ 2 = ∑ i in s₁ \ s₂, ‖f i‖ ^ 2 + ∑ i in s₂ \ s₁, ‖f i‖ ^ 2
begin rw [← finset.sum_sdiff_sub_sum_sdiff, sub_eq_add_neg, ← finset.sum_neg_distrib], let F : Π i, G i := λ i, if i ∈ s₁ then f i else - (f i), have hF₁ : ∀ i ∈ s₁ \ s₂, F i = f i := λ i hi, if_pos (finset.sdiff_subset _ _ hi), have hF₂ : ∀ i ∈ s₂ \ s₁, F i = - f i := λ i hi, if_neg (finset.mem_sdiff.mp hi).2,...
lemma
orthogonal_family.norm_sq_diff_sum
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "disjoint", "disjoint_sdiff_sdiff", "finset", "finset.sdiff_subset", "linear_isometry.map_neg" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
orthogonal_family.summable_iff_norm_sq_summable [complete_space E] (f : Π i, G i) : summable (λ i, V i (f i)) ↔ summable (λ i, ‖f i‖ ^ 2)
begin classical, simp only [summable_iff_cauchy_seq_finset, normed_add_comm_group.cauchy_seq_iff, real.norm_eq_abs], split, { intros hf ε hε, obtain ⟨a, H⟩ := hf _ (sqrt_pos.mpr hε), use a, intros s₁ hs₁ s₂ hs₂, rw ← finset.sum_sdiff_sub_sum_sdiff, refine (abs_sub _ _).trans_lt _, ha...
lemma
orthogonal_family.summable_iff_norm_sq_summable
analysis.inner_product_space
src/analysis/inner_product_space/basic.lean
[ "algebra.direct_sum.module", "analysis.complex.basic", "analysis.convex.uniform", "analysis.normed_space.completion", "analysis.normed_space.bounded_linear_maps", "linear_algebra.bilinear_form" ]
[ "abs_lt_of_sq_lt_sq'", "abs_of_nonneg", "abs_sub", "add_tsub_cancel_right", "complete_space", "finset.abs_sum_of_nonneg'", "finset.inter_subset_left", "finset.inter_subset_right", "half_pos", "le_inf", "real.norm_eq_abs", "sq_lt_sq", "sq_nonneg", "sq_pos_of_pos", "summable", "summable_...
A family `f` of mutually-orthogonal elements of `E` is summable, if and only if `(λ i, ‖f i‖ ^ 2)` is summable.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83