Fderiv cross commute
Space.fderiv_cross_commute
Plain-language statement
Cross product and fderiv commute.
Exact Lean statement
lemma fderiv_cross_commute {t : Time} {s : EuclideanSpace ℝ (Fin 3)}
{f : Time → EuclideanSpace ℝ (Fin 3)} (hf : Differentiable ℝ f) :
s ⨯ₑ₃ (fderiv ℝ (fun t' => f t') t) 1
= fderiv ℝ (fun t' => s ⨯ₑ₃ (f t')) t 1Formal artifact
Lean source
lemma fderiv_cross_commute {t : Time} {s : EuclideanSpace ℝ (Fin 3)} {f : Time → EuclideanSpace ℝ (Fin 3)} (hf : Differentiable ℝ f) : s ⨯ₑ₃ (fderiv ℝ (fun t' => f t') t) 1 = fderiv ℝ (fun t' => s ⨯ₑ₃ (f t')) t 1 := by have h (i j : Fin 3) : s i * (fderiv ℝ (fun u => f u) t) 1 j - s j * (fderiv ℝ (fun u => f u) t) 1 i = (fderiv ℝ (fun t => s i * f t j - s j * f t i) t) 1:= by rw [fderiv_fun_sub, fderiv_const_mul, fderiv_const_mul] · simp only [FunLike.coe_sub, FunLike.coe_smul, Pi.sub_apply, Pi.smul_apply, smul_eq_mul] rw [Time.fderiv_euclid, Time.fderiv_euclid] · intro i repeat fun_prop · fun_prop · fun_prop · fun_prop · fun_prop · fun_prop rw [crossProduct] ext i fin_cases i <;> · simp [Nat.succ_eq_add_one, Nat.reduceAdd, Fin.isValue, WithLp.equiv_apply, LinearMap.mk₂_apply, Fin.reduceFinMk, WithLp.equiv_symm_apply, PiLp.toLp_apply, cons_val] rw [h] simp only [Fin.isValue] rw [← Time.fderiv_euclid] simp [Fin.isValue, cons_val_zero] apply Time.differentiable_euclid intro i fin_cases i · simp [Fin.zero_eta, Fin.isValue] fun_prop · simp [Fin.isValue] fun_prop · simp [Fin.isValue] fun_prop- Project
- Physlib
- License
- Apache-2.0
- Commit
- dd43e9e65791
- Source
- Physlib/SpaceAndTime/Space/CrossProduct.lean:62-98
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