Mutating arrays not supported

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To write adjoints you will need to read the manual, and probably look at some of these examples.

Zygote’s errors are usually from 10 layers underground, I don’t quite know why each of these fails.

But I have a package solution:

julia> using Tullio, ForwardDiff, Zygote

julia> fs = [sin,cos,tan];

julia> rowmap(fs, x) = @tullio y[r,c] := begin
         f = getindex(fs, r)
         @inbounds f(x[r,c])
       end grad=Dual;

julia> gradient(x -> sum(rowmap(fs, x)), ones(3,10))[1]
3×10 Array{Float64,2}:
  0.540302   0.540302   0.540302   0.540302  …   0.540302   0.540302   0.540302   0.540302
 -0.841471  -0.841471  -0.841471  -0.841471     -0.841471  -0.841471  -0.841471  -0.841471
  3.42552    3.42552    3.42552    3.42552       3.42552    3.42552    3.42552    3.42552

This is probably quite efficient, compared to making slices. If you check axes(fs,1)==axes(x,1) then you could use @inbounds getindex(fs, r).

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