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chore(linear_algebra/basic, analysis/normed_space/operator_norm): bun…
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…dle another argument into the homs (#5899)

Co-authored-by: sgouezel <sebastien.gouezel@univ-rennes1.fr>
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eric-wieser and sgouezel committed Feb 9, 2021
1 parent 7f11d72 commit 117e729
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Showing 2 changed files with 30 additions and 25 deletions.
30 changes: 13 additions & 17 deletions src/analysis/normed_space/operator_norm.lean
Expand Up @@ -683,23 +683,19 @@ continuous_linear_map.homothety_norm _ c.norm_smul_right_apply

variables (𝕜 F)

/-- The linear map obtained by applying a continuous linear map at a given vector. -/
def applyₗ (v : E) : (E →L[𝕜] F) →ₗ[𝕜] F :=
{ to_fun := λ f, f v,
map_add' := λ f g, f.add_apply g v,
map_smul' := λ x f, f.smul_apply x v }

lemma continuous_applyₗ (v : E) : continuous (continuous_linear_map.applyₗ 𝕜 F v) :=
begin
apply (continuous_linear_map.applyₗ 𝕜 F v).continuous_of_bound,
intro f,
rw mul_comm,
exact f.le_op_norm v,
end

/-- The continuous linear map obtained by applying a continuous linear map at a given vector. -/
def apply (v : E) : (E →L[𝕜] F) →L[𝕜] F :=
⟨continuous_linear_map.applyₗ 𝕜 F v, continuous_linear_map.continuous_applyₗ _ _ _⟩
/-- The continuous linear map obtained by applying a continuous linear map at a given vector.
This is the continuous version of `linear_map.applyₗ`. -/
def apply : E →L[𝕜] (E →L[𝕜] F) →L[𝕜] F :=
linear_map.mk_continuous
{ to_fun := λ v, linear_map.mk_continuous
{ to_fun := λ f, f v,
map_add' := λ f g, f.add_apply g v,
map_smul' := λ x f, f.smul_apply x v }
∥v∥ (λ f, by simpa [mul_comm] using f.le_op_norm v),
map_add' := λ _ _, ext $ λ f, f.map_add _ _,
map_smul' := λ _ _, ext $ λ f, f.map_smul _ _, }
1 $ λ x, op_norm_le_bound _ (by simp) (λ f, by simpa [mul_comm] using f.le_op_norm x)

variables {𝕜 F}

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25 changes: 17 additions & 8 deletions src/linear_algebra/basic.lean
Expand Up @@ -330,11 +330,15 @@ variable (S)

/-- Applying a linear map at `v : M`, seen as `S`-linear map from `M →ₗ[R] M₂` to `M₂`.
See `applyₗ` for a version where `S = R` -/
def applyₗ' (v : M) : (M →ₗ[R] M₂) →ₗ[S] M₂ :=
{ to_fun := λ f, f v,
map_add' := λ f g, f.add_apply g v,
map_smul' := λ x f, f.smul_apply x v }
See `linear_map.applyₗ` for a version where `S = R`. -/
@[simps]
def applyₗ' : M →+ (M →ₗ[R] M₂) →ₗ[S] M₂ :=
{ to_fun := λ v,
{ to_fun := λ f, f v,
map_add' := λ f g, f.add_apply g v,
map_smul' := λ x f, f.smul_apply x v },
map_zero' := linear_map.ext $ λ f, f.map_zero,
map_add' := λ x y, linear_map.ext $ λ f, f.map_add _ _ }

end semimodule

Expand Down Expand Up @@ -479,9 +483,14 @@ def comp_right (f : M₂ →ₗ[R] M₃) : (M →ₗ[R] M₂) →ₗ[R] (M →
λ _ _, linear_map.ext $ λ _, f.3 _ _⟩

/-- Applying a linear map at `v : M`, seen as a linear map from `M →ₗ[R] M₂` to `M₂`.
See also `linear_map.applyₗ'` for a version that works with two different semirings. -/
def applyₗ (v : M) : (M →ₗ[R] M₂) →ₗ[R] M₂ :=
applyₗ' R v
See also `linear_map.applyₗ'` for a version that works with two different semirings.
This is the `linear_map` version of `add_monoid_hom.eval`. -/
@[simps]
def applyₗ : M →ₗ[R] (M →ₗ[R] M₂) →ₗ[R] M₂ :=
{ to_fun := λ v, { to_fun := λ f, f v, ..applyₗ' R v },
map_smul' := λ x y, linear_map.ext $ λ f, f.map_smul _ _,
..applyₗ' R }

end comm_semiring

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