The ScaledPlan like e.g. the result of plan_fft has no field region, leading to an error when attempting to AD it via Zygote. Zygote (which depends on AbstractFFT) is requiring a region subfield.
Example
begin
using Flux
using Zygote
using LinearAlgebra
using FFTW
end
N = 15
data = rand(Float64, N)
FT = plan_fft(data) # e.g. plan_dct / plan_idct would work
iFT= plan_ifft(data)
m = Chain(x->FT*x, Dense(N,N), x->iFT*x)
loss(x,y) = sum(abs2,m(x) .- y)
loss(data,data) # precompile
grads = gradient(() -> loss(data, data), params(m))
The
ScaledPlanlike e.g. the result ofplan_ffthas no fieldregion, leading to an error when attempting to AD it via Zygote. Zygote (which depends on AbstractFFT) is requiring aregionsubfield.Example