Matrix(Diagonal)

Author: mcabbott

src/lib/array.jl

@@ -420,6 +420,9 @@ end
 LinearAlgebra.diagm(x::Pair{<:Integer, <:TrackedVector}) = track(diagm, x...)
 @grad diagm(i, x) = diagm(i => data(x)), Δ -> (nothing, diag(Δ, i))
 
+# fix Matrix(Diagonal(param([1,2,3]))) after https://github.com/JuliaLang/julia/pull/44615
+(::Type{Matrix})(d::Diagonal{<:Any,<:TrackedArray}) = diagm(0 => d.diag)
+
 x::TrackedMatrix  * y::AbstractMatrix = track(*, x, y)
 x::AbstractMatrix * y::TrackedMatrix  = track(*, x, y)
 x::TrackedMatrix  * y::TrackedMatrix  = track(*, x, y)

test/tracker.jl

@@ -172,6 +172,7 @@ end
 @test gradtest(kron, rand(5,2), rand(3,2), rand(8,2))
 
 @test gradtest(x -> diagm(0 => x), rand(3))
+@test gradtest(x -> Matrix(Diagonal(x)), rand(3))
 
 @test gradtest(W -> inv(log.(W * W)), (5,5))
 @test gradtest((A, B) -> A / B , (1,5), (5,5))