nan & complex fixes

Author: mcabbott

src/dropout.jl

@@ -72,23 +72,25 @@ end
 
 # This is the easy case in that we can safely use the output array for random numbers.
 function _dropout!(rng::AbstractRNG, dst::AbstractArray, src::AbstractArray, p::Real, dims::Colon)
-    val = convert(eltype(dst), 1/(1-p))
+    T = real(eltype(dst))
+    val = convert(T, 1/(1-p))
     rand!(rng, dst)
     ## This is what we want, but it hits a SIMD bug, solved by _fast_broadcast!
     # dst .= (dst.>p) .* val .* src
     _fast_broadcast!(dst, src) do q, x
-        (q>p) * val * x
+        ((real(q)>p) * val) * x
     end
     dst
 end
 
 # For other dims, we we do need to allocate something.
 function _dropout!(rng::AbstractRNG, dst::AbstractArray, src::AbstractArray, p::Real, dims)
-    tmp = similar(dst, ntuple(d -> d in dims ? size(src,d) : 1, ndims(src)))
+    T = real(eltype(dst))
+    tmp = similar(dst, T, ntuple(d -> d in dims ? size(src,d) : 1, ndims(src)))
     rand!(rng, tmp)
-    val = convert(eltype(dst), 1/(1-p))
+    val = convert(T, 1/(1-p))
     ## One-pass strategy -- faster on GPU
-    dst .= (tmp.>p) .* val .* src
+    dst .= ((tmp.>p) .* val) .* src
     ## Two-pass strategy -- slightly faster on some CPUs?
     # _fast_broadcast!(tmp) do q
     #     (q>p) * val
@@ -99,18 +101,18 @@ end
 # The gradient needs to keep the random choices made, thus store at least a BitArray,
 # but the following way turns out to be faster & simpler:
 function ChainRulesCore.rrule(::typeof(dropout), rng::AbstractRNG, A::AbstractArray, p::Real; dims = :)
-    T = float(eltype(A))
+    T = float(real(eltype(A)))
     val = convert(T, 1/(1-p))
     keep = if dims isa Colon
         similar(A, T) 
     else
         similar(A, T, ntuple(d -> d in dims ? size(A,d) : 1, ndims(A)))
     end
     rand!(rng, keep)
-    Y = @. (keep>p) * A * val
+    Y = @. ((keep>p) * val) * A
     function dropout_back(Δ)
         dY = unthunk(Δ)
-        dA = @. (keep>p) * dY * val
+        dA = @. ((keep>p) * val) * dY
         (NoTangent(), NoTangent(), dA, NoTangent())
     end
     return Y, dropout_back

test/dropout.jl

@@ -16,27 +16,49 @@ using Zygote, StableRNGs, ChainRulesCore
     @test size(@inferred dropout(rng, x1, 0.1; dims=2)) == (3, 4)
 
     # Values
+    @test dropout(x1, 0) == x1
+    @test dropout(x1.+0im, 0) == x1
+    @test dropout(x1, 1) == zero.(x1)
+    @test dropout(x1.+im, 1) == zero.(x1)
+
     d45 = dropout(trues(100, 100, 100), 0.45)
     @test mean(d45) ≈ 1 atol=1e-2
     dpi2 = dropout(fill(pi, 1000), 0.2)
     @test sort(unique(dpi2)) ≈ [0, 5pi/4]
     d33 = dropout(fill(3, 10, 1000), 0.3, dims=2)
     @test sort(unique(vec(d33))) ≈ [0, 3/(1-0.3)]
 
+    # Complex -- not worth too much optimisation, but should work!
+    x2 = [1.0+0im,2.0+1im,3.0+3im]  # from Flux's tests
+    @test dropout(x, 0.5) isa Vector{ComplexF64}
+    @test dropout(x, 0.5; dims=1) isa Vector{ComplexF64}
+
     # Gradient rule
     y, back = rrule(dropout, rng, hcat(trues(1000), falses(1000)), 0.45)
     dx = back(fill(3, 1000, 2))[3]
     @test !all(iszero, dx[:,2])  # this is why we save the random choices
     @test sort(unique(vec(dx))) ≈ [0, 3/(1-0.45)]
 
+    y2, back2 = rrule(dropout, rng, x2, 0.5)
+    @test y2 isa Vector{ComplexF64}
+    @test back2(one.(y2))[3] isa Vector{ComplexF64}
+
     @testset "Zygote" begin
         @test Zygote.gradient(x -> sum(dropout(x, 0.3)), x1)[1] isa Matrix{Float32}
         @test Zygote.gradient(x -> sum(dropout(rng, x, 0.3)), x1)[1] isa Matrix{Float32}
         @test Zygote.gradient(x -> sum(dropout(x, 0.3, dims=1)), x1)[1] isa Matrix{Float32}
 
+        # p=0 & p=1
+        @test Zygote.gradient(x -> sum(dropout(x, 0)), x1)[1] == ones(3,4)
+        @test Zygote.gradient(x -> sum(dropout(x, 1)), x1)[1] == zeros(3,4)
+
+        # Second order
         f1(x) = sum(dropout(x, 0.5))
         @test_broken Zygote.hessian(f1, [1.0,2.0,3.0]) == zeros(3, 3)  # forward over reverse
         @test Zygote.hessian_reverse(f1, [1.0,2.0,3.0]) == zeros(3, 3)
     end
-end
 
+    # Errors
+    @test_throws ArgumentError dropout(x1, -1)
+    @test_throws ArgumentError dropout(x1, 2)
+end