Make rand_tangent on adjoint an transpose return natural

Project.toml

@@ -1,6 +1,6 @@
 name = "FiniteDifferences"
 uuid = "26cc04aa-876d-5657-8c51-4c34ba976000"
-version = "0.12.7"
+version = "0.12.8"
 
 [deps]
 ChainRulesCore = "d360d2e6-b24c-11e9-a2a3-2a2ae2dbcce4"

src/difference.jl

@@ -18,7 +18,10 @@ difference(::Real, ::T, ::T) where {T<:Integer} = NoTangent()
 
 difference(ε::Real, y::T, x::T) where {T<:Number} = (y - x) / ε
 
-difference(ε::Real, y::T, x::T) where {T<:StridedArray} = difference.(ε, y, x)
+# we are a bit more relaced for AbstractArrays as they naturally represent a vector space
+difference(ε::Real, y::AbstractArray, x) = difference.(ε, y, x)
+# resolve ambiguity
+difference(ε::Real, y::T, x::T) where {T<:AbstractArray} = difference.(ε, y, x)
 
 function difference(ε::Real, y::T, x::T) where {T<:Tuple}
     return Tangent{T}(difference.(ε, y, x)...)

src/rand_tangent.jl

@@ -13,11 +13,13 @@ rand_tangent(rng::AbstractRNG, x::Integer) = NoTangent()
 
 rand_tangent(rng::AbstractRNG, x::T) where {T<:Number} = randn(rng, T)
 
-# TODO: right now Julia don't allow `randn(rng, BigFloat)` 
+# TODO: right now Julia don't allow `randn(rng, BigFloat)`
 # see: https://github.com/JuliaLang/julia/issues/17629
 rand_tangent(rng::AbstractRNG, ::BigFloat) = big(randn(rng))
 
 rand_tangent(rng::AbstractRNG, x::StridedArray) = rand_tangent.(Ref(rng), x)
+rand_tangent(rng::AbstractRNG, x::Adjoint) = adjoint(rand_tangent(rng, parent(x)))
+rand_tangent(rng::AbstractRNG, x::Transpose) = transpose(rand_tangent(rng, parent(x)))
 
 function rand_tangent(rng::AbstractRNG, x::T) where {T<:Tuple}
     return Tangent{T}(rand_tangent.(Ref(rng), x)...)

test/difference.jl

@@ -1,13 +1,5 @@
 using FiniteDifferences: rand_tangent, difference
 
-function test_difference(ε::Real, x, dx)
-    y = x + ε * dx
-    dx_diff = difference(ε, y, x)
-    # TODO: `@test isapprox(dx, dx_diff)` once `isapprox` is defined appropriately
-    # see https://github.com/JuliaDiff/ChainRulesCore.jl/issues/184
-    @test typeof(dx) == typeof(dx_diff)
-end
-
 @testset "difference" begin
 
     @testset "Primal: $(typeof(x))" for (ε, x) in [
@@ -56,7 +48,17 @@ end
         (randn(), Adjoint(randn(ComplexF64, 3, 3))),
         (randn(), Transpose(randn(3))),
     ]
-        test_difference(ε, x, rand_tangent(x))
+        # Construct a value that should be equal to the difference and check that it is
+        dx = rand_tangent(x)
+        y = x + ε * dx
+        dx_diff = difference(ε, y, x)
+
+        if x isa AbstractArray{<:Number} || x isa Number
+            @test x + dx ≈ x + dx_diff
+        else
+            #  hard to check value if don't overload `≈` so for now we  just check type
+            @test typeof(dx) == typeof(dx_diff)
+        end
     end
 
     # Ensure struct fallback errors for non-struct types.

test/rand_tangent.jl

@@ -24,6 +24,11 @@ using FiniteDifferences: rand_tangent
         (randn(Complex{Float32}, 5, 4), Matrix{Complex{Float32}}),
         ([randn(5, 4), 4.0], Vector{Any}),
 
+        # Wrapper Arrays
+        (randn(5, 4)', Adjoint{Float64, Matrix{Float64}}),
+        (transpose(randn(5, 4)), Transpose{Float64, Matrix{Float64}}),
+
+
         # Tuples.
         ((4.0, ), Tangent{Tuple{Float64}}),
         ((5.0, randn(3)), Tangent{Tuple{Float64, Vector{Float64}}}),
@@ -66,20 +71,19 @@ using FiniteDifferences: rand_tangent
             Hermitian(randn(ComplexF64, 1, 1)),
             Tangent{Hermitian{ComplexF64, Matrix{ComplexF64}}},
         ),
-        (
-            Adjoint(randn(ComplexF64, 3, 3)),
-            Tangent{Adjoint{ComplexF64, Matrix{ComplexF64}}},
-        ),
-        (
-            Transpose(randn(3)),
-            Tangent{Transpose{Float64, Vector{Float64}}},
-        ),
     ]
         @test rand_tangent(rng, x) isa T_tangent
         @test rand_tangent(x) isa T_tangent
-        @test x + rand_tangent(rng, x) isa typeof(x)
     end
 
-    # Ensure struct fallback errors for non-struct types.
-    @test_throws ArgumentError invoke(rand_tangent, Tuple{AbstractRNG, Any}, rng, 5.0)
+    @testset "erroring cases" begin
+        # Ensure struct fallback errors for non-struct types.
+        @test_throws ArgumentError invoke(rand_tangent, Tuple{AbstractRNG, Any}, rng, 5.0)
+    end
+
+    @testset "compsition of addition" begin
+        x = Foo(1.5, 2, Foo(1.1, 3, [1.7, 1.4, 0.9]))
+        @test x + rand_tangent(x) isa typeof(x)
+        @test x + (rand_tangent(x) + rand_tangent(x)) isa typeof(x)
+    end
 end