Documentation

Mathlib.Geometry.Euclidean.Inversion.Calculus

Derivative of the inversion #

In this file we prove a formula for the derivative of EuclideanGeometry.inversion c R.

Implementation notes #

Since fderiv and related definitions do not work for affine spaces, we deal with an inner product space in this file.

Keywords #

inversion, derivative

theorem ContDiffWithinAt.inversion {E : Type u_1} {F : Type u_2} [NormedAddCommGroup E] [NormedSpace ℝ E] [NormedAddCommGroup F] [InnerProductSpace ℝ F] {c x : E → F} {R : E → ℝ} {s : Set E} {a : E} {n : ℕ∞} (hc : ContDiffWithinAt ℝ (↑n) c s a) (hR : ContDiffWithinAt ℝ (↑n) R s a) (hx : ContDiffWithinAt ℝ (↑n) x s a) (hne : x a ≠ c a) :
ContDiffWithinAt ℝ (↑n) (fun (a : E) => EuclideanGeometry.inversion (c a) (R a) (x a)) s a
theorem ContDiffOn.inversion {E : Type u_1} {F : Type u_2} [NormedAddCommGroup E] [NormedSpace ℝ E] [NormedAddCommGroup F] [InnerProductSpace ℝ F] {c x : E → F} {R : E → ℝ} {s : Set E} {n : ℕ∞} (hc : ContDiffOn ℝ (↑n) c s) (hR : ContDiffOn ℝ (↑n) R s) (hx : ContDiffOn ℝ (↑n) x s) (hne : ∀ a ∈ s, x a ≠ c a) :
ContDiffOn ℝ (↑n) (fun (a : E) => EuclideanGeometry.inversion (c a) (R a) (x a)) s
theorem ContDiffAt.inversion {E : Type u_1} {F : Type u_2} [NormedAddCommGroup E] [NormedSpace ℝ E] [NormedAddCommGroup F] [InnerProductSpace ℝ F] {c x : E → F} {R : E → ℝ} {a : E} {n : ℕ∞} (hc : ContDiffAt ℝ (↑n) c a) (hR : ContDiffAt ℝ (↑n) R a) (hx : ContDiffAt ℝ (↑n) x a) (hne : x a ≠ c a) :
ContDiffAt ℝ (↑n) (fun (a : E) => EuclideanGeometry.inversion (c a) (R a) (x a)) a
theorem ContDiff.inversion {E : Type u_1} {F : Type u_2} [NormedAddCommGroup E] [NormedSpace ℝ E] [NormedAddCommGroup F] [InnerProductSpace ℝ F] {c x : E → F} {R : E → ℝ} {n : ℕ∞} (hc : ContDiff ℝ (↑n) c) (hR : ContDiff ℝ (↑n) R) (hx : ContDiff ℝ (↑n) x) (hne : ∀ (a : E), x a ≠ c a) :
ContDiff ℝ ↑n fun (a : E) => EuclideanGeometry.inversion (c a) (R a) (x a)
theorem DifferentiableWithinAt.inversion {E : Type u_1} {F : Type u_2} [NormedAddCommGroup E] [NormedSpace ℝ E] [NormedAddCommGroup F] [InnerProductSpace ℝ F] {c x : E → F} {R : E → ℝ} {s : Set E} {a : E} (hc : DifferentiableWithinAt ℝ c s a) (hR : DifferentiableWithinAt ℝ R s a) (hx : DifferentiableWithinAt ℝ x s a) (hne : x a ≠ c a) :
DifferentiableWithinAt ℝ (fun (a : E) => EuclideanGeometry.inversion (c a) (R a) (x a)) s a
theorem DifferentiableOn.inversion {E : Type u_1} {F : Type u_2} [NormedAddCommGroup E] [NormedSpace ℝ E] [NormedAddCommGroup F] [InnerProductSpace ℝ F] {c x : E → F} {R : E → ℝ} {s : Set E} (hc : DifferentiableOn ℝ c s) (hR : DifferentiableOn ℝ R s) (hx : DifferentiableOn ℝ x s) (hne : ∀ a ∈ s, x a ≠ c a) :
DifferentiableOn ℝ (fun (a : E) => EuclideanGeometry.inversion (c a) (R a) (x a)) s
theorem DifferentiableAt.inversion {E : Type u_1} {F : Type u_2} [NormedAddCommGroup E] [NormedSpace ℝ E] [NormedAddCommGroup F] [InnerProductSpace ℝ F] {c x : E → F} {R : E → ℝ} {a : E} (hc : DifferentiableAt ℝ c a) (hR : DifferentiableAt ℝ R a) (hx : DifferentiableAt ℝ x a) (hne : x a ≠ c a) :
DifferentiableAt ℝ (fun (a : E) => EuclideanGeometry.inversion (c a) (R a) (x a)) a
theorem Differentiable.inversion {E : Type u_1} {F : Type u_2} [NormedAddCommGroup E] [NormedSpace ℝ E] [NormedAddCommGroup F] [InnerProductSpace ℝ F] {c x : E → F} {R : E → ℝ} (hc : Differentiable ℝ c) (hR : Differentiable ℝ R) (hx : Differentiable ℝ x) (hne : ∀ (a : E), x a ≠ c a) :
Differentiable ℝ fun (a : E) => EuclideanGeometry.inversion (c a) (R a) (x a)
theorem EuclideanGeometry.hasFDerivAt_inversion {F : Type u_2} [NormedAddCommGroup F] [InnerProductSpace ℝ F] {c x : F} {R : ℝ} (hx : x ≠ c) :
HasFDerivAt (inversion c R) ((R / dist x c) ^ 2 • ↑↑(ℝ ∙ (x - c))ᗮ.reflection) x

Formula for the Fréchet derivative of EuclideanGeometry.inversion c R.