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JuliaGeometry / Rotations.jl

Julia implementations for different rotation parameterizations
https://juliageometry.github.io/Rotations.jl
MIT License
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Jacobian of `exp(RotationVecGenerator(...))` at 0 results in `NaN` #280

Open cafaxo opened 9 months ago

cafaxo commented 9 months ago

This should not result in NaN:

julia> f(p) = exp(RotationVecGenerator(p[1], p[2], p[3]));

julia> ForwardDiff.jacobian(f, [0.0, 0.0, 0.0])
9×3 Matrix{Float64}:
 NaN  NaN  NaN
 NaN  NaN  NaN
 NaN  NaN  NaN
 NaN  NaN  NaN
 NaN  NaN  NaN
 NaN  NaN  NaN
 NaN  NaN  NaN
 NaN  NaN  NaN
 NaN  NaN  NaN

The correct output is

 julia> f2(p) = exp(SMatrix(RotationVecGenerator(p[1], p[2], p[3])));

julia> ForwardDiff.jacobian(f2, [0.0, 0.0, 0.0])
9×3 Matrix{Float64}:
  0.0   0.0   0.0
  0.0   0.0   1.0
  0.0  -1.0   0.0
  0.0   0.0  -1.0
  0.0   0.0   0.0
  1.0   0.0   0.0
  0.0   1.0   0.0
 -1.0   0.0   0.0
  0.0   0.0   0.0