Another update from ingydotnet^djgoku

Task/Dot-product/Elixir/dot-product.elixir

@@ -0,0 +1,11 @@
+defmodule Vector do
+  def dot_product(a,b) when length(a)==length(b), do: dot_product(a,b,0)
+  def dot_product(_,_) do
+    raise ArgumentError, message: "Vectors must have the same length."
+  end
+
+  defp dot_product([],[],product), do: product
+  defp dot_product([h1|t1], [h2|t2], product), do: dot_product(t1, t2, product+h1*h2)
+end
+
+IO.puts Vector.dot_product([1,3,-5],[4,-2,-1])