+ Operator not defined for ForwardDiff.Dual{...}

[yosinlpet]

Hi,

I'm encountering an issue when trying to find the jacobian of a vector field.

1  function f(qx, qy, q, d)                                                 
2        K = length(q)                                                               
3        ∑q = cumsum(q)                                                              
4        coeff = (.5 + d)/K                                                          
5        A = [cos.(∑q) sin.(∑q)]                                                     
6        return [qx, qy] .+ coeff.*A'*centrosymmetric(K)                              
7  end  
8
9  f(q, d) = f(q[1], q[2], q[3:end], d)
10
11 ForwardDiff.jacobian(x->f(x, d), q)

where q is an array of TF <: Real when f is called outside of ForwardDiff functions.
centrosymmetric(K) simply returns a KxK centrosymmetric matrix filled with integer values.

This used to work fine on julia 1.7.2 but I just upgraded to 1.8.1 and it throws the following error.

ERROR: LoadError: + not defined for ForwardDiff.Dual{ForwardDiff.Tag{MyCustomPackage.var"#337#339"{Float64}, Float64}, Float64, 7}

The slack trace says line 6 is problematic...
I find it weird: if i get rid of the addition and only keep the matrix multiplication, I don't get the error even though multiplying matrices requires its fair share of additions.

Has anyone an idea of how to easily fix the issue?
I could modify A and add a line filled with 1s on top of the centrosymmetric matrix to embed the addition in the matrix product but it seems inferior to broadcasting + to me...

[yosinlpet]

return muladd(coeff*A', centrosymmetric(K), [qx, qy]) gives the same result

[KristofferC]

I think this might be a bug in 1.8.1 that I think should be fixed in the upcoming 1.8.2. What OS do you run? I can give you a link to a Julia build that you can test out.

[yosinlpet]

Mac Os Monterey 12.5.1

[KristofferC]

Try https://buildkite.com/organizations/julialang/pipelines/julia-release-1-dot-8/builds/230/jobs/01835fb0-7abd-4e8c-b9a1-efbc824b6b38/artifacts/01835fc2-bf20-4c32-8baf-26c9ccea8b55

[yosinlpet]

What is the best way to build from binaries?
If i just do

rm /usr/local/bin/julia
sudo ln -s /path/to/julia/bin/julia /usr/local/bin/julia

Then I get
Warning: Expected non-existent /path/to/julia-285b75c30b/share/julia to be your Julia directory.

Apart from that it is working again, thanks!

[KristofferC]

Just extract and run the bin/julia in the directory.