autodiff
R : Type
inst✝² : RealScalar R
inst✝¹ : MeasureSpace R
inst✝ : PlainDataType R
⊢ (fun x =>
      let dg := ∂ (θ:=x), (cos θ, sin θ);
      let dg' := semiAdjoint R dg;
      sqrt (det R (dg' ∘ dg))) =
    1
R : Type
inst✝² : RealScalar R
inst✝¹ : MeasureSpace R
inst✝ : PlainDataType R
⊢ (fun x =>
      let s := -sin x;
      let c := cos x;
      let dg' := semiAdjoint R fun dx => (dx * s, dx * c);
      sqrt ((dg' ∘ fun dx => (dx * s, dx * c)) 1)) =
    1