Merge pull request #130 from merckxiaan/master

Make softmax! dimension-agnostic

Author: MikeInnes

src/softmax.jl

@@ -17,7 +17,10 @@ independent.
       0.244728
       0.665241
 """
-softmax(xs) = softmax!(similar(xs), xs)
+function softmax(xs::AbstractArray{T}; dims=1) where {T}
+    max = maximum(xs, dims=dims)
+    out = exp.(xs .- max) ./ sum(exp.(xs .- max), dims=dims)
+end
 
 function softmax!(out::AbstractVecOrMat{T}, xs::AbstractVecOrMat{T}) where {T}
     @inbounds for j = 1:size(xs, 2)
@@ -50,8 +53,10 @@ function ∇softmax!(out::AbstractVecOrMat, Δ::AbstractVecOrMat, xs::AbstractVe
     sf = softmax(xs)
     out .= sf .* (Δ .- sum(Δ .*sf, dims = 1))
 end
-
-∇softmax(Δ, xs) = ∇softmax!(similar(Δ), Δ, xs)
+function ∇softmax(Δ, xs; dims=1) 
+    sf = softmax(xs, dims=dims)
+    out = sf .* (Δ .- sum(Δ .* sf, dims=dims))
+end
 ∇softmax!(Δ, xs) = ∇softmax!(Δ, Δ, xs)