From 29787eba452a0e12e7c152fe7ded67393f18a8b7 Mon Sep 17 00:00:00 2001
From: Mike J Innes <mike.j.innes@gmail.com>
Date: Tue, 12 Dec 2017 17:23:15 +0000
Subject: [PATCH] fixes #114

---
 src/tracker/lib.jl | 9 +++++++++
 test/tracker.jl    | 2 ++
 2 files changed, 11 insertions(+)

diff --git a/src/tracker/lib.jl b/src/tracker/lib.jl
index ab250e39..f3221bd8 100644
--- a/src/tracker/lib.jl
+++ b/src/tracker/lib.jl
@@ -58,6 +58,15 @@ Base.findfirst(xs::TrackedArray, args...) = findfirst(xs.data, args...)
 Base.mean(xs::TrackedArray) = TrackedArray(Call(mean, xs), toarray(xs.data, mean(xs.data)))
 Base.mean(xs::TrackedArray, region) = TrackedArray(Call(mean, xs, region))
 
+LinAlg.dot(xs::TrackedVector, ys::TrackedVector) = TrackedArray(Call(dot, xs, ys), toarray(xs.data, dot(data(xs), data(ys))))
+LinAlg.dot(xs::AbstractVector, ys::TrackedVector) = TrackedArray(Call(dot, xs, ys), toarray(xs.data, dot(data(xs), data(ys))))
+LinAlg.dot(xs::TrackedVector, ys::AbstractVector) = TrackedArray(Call(dot, xs, ys), toarray(xs.data, dot(data(xs), data(ys))))
+
+function back(::typeof(dot), Δ, xs, ys)
+  @back(xs, Δ.*ys)
+  @back(ys, Δ.*xs)
+end
+
 # Hacks to get std working
 Base.std(x::TrackedArray; mean = Base.mean(x)) =
   sqrt.(sum((x .- mean).^2) ./ (length(x)-1))
diff --git a/test/tracker.jl b/test/tracker.jl
index 7d9ef4f5..ac031915 100644
--- a/test/tracker.jl
+++ b/test/tracker.jl
@@ -38,6 +38,8 @@ end
 @test gradtest(x -> std(x), rand(5,5))
 @test gradtest(x -> std(x, 1), rand(5,5))
 
+@test gradtest((x, y) -> x .* y, rand(5), rand(5))
+
 @test gradtest(rand(5)) do x
   y = x.^2
   2y + x