1 files changed, 61 insertions, 0 deletions
diff --git a/contrib/lua-torch/nn/DotProduct.lua b/contrib/lua-torch/nn/DotProduct.lua
new file mode 100644
index 000000000..ccd347e6b
--- /dev/null
+++ b/contrib/lua-torch/nn/DotProduct.lua
@@ -0,0 +1,61 @@
+local DotProduct, parent = torch.class('nn.DotProduct', 'nn.Module')
+
+function DotProduct:__init()
+   parent.__init(self)
+   self.gradInput = {torch.Tensor(), torch.Tensor()}
+end
+
+function DotProduct:updateOutput(input)
+   local input1, input2 = input[1], input[2]
+   if input1:dim() == 1 then
+      -- convert non batch input to batch input
+      input1 = input1:view(1,-1)
+      input2 = input2:view(1,-1)
+   end
+   if not self.buffer then
+      self.buffer = input1.new()
+   end
+   self.buffer:cmul(input1, input2)
+   self.output:sum(self.buffer, 2)
+   self.output:resize(input1:size(1))
+   return self.output
+end
+
+function DotProduct:updateGradInput(input, gradOutput)
+   local v1 = input[1]
+   local v2 = input[2]
+   local not_batch = false
+
+   if #self.gradInput ~= 2 then
+     self.gradInput[1] = self.gradInput[1] or input[1].new()
+     self.gradInput[2] = self.gradInput[2] or input[2].new()
+   end
+
+   if v1:dim() == 1 then
+      v1 = v1:view(1,-1)
+      v2 = v2:view(1,-1)
+      not_batch = true
+   end
+
+   local gw1 = self.gradInput[1]
+   local gw2 = self.gradInput[2]
+   gw1:resizeAs(v1):copy(v2)
+   gw2:resizeAs(v2):copy(v1)
+
+   local go = gradOutput:view(-1,1):expandAs(v1)
+   gw1:cmul(go)
+   gw2:cmul(go)
+
+   if not_batch then
+      -- unbatch gradInput
+      self.gradInput[1]:set(gw1:select(1,1))
+      self.gradInput[2]:set(gw2:select(1,1))
+   end
+
+   return self.gradInput
+end
+
+function DotProduct:clearState()
+   if self.buffer then self.buffer:set() end
+   return parent.clearState(self)
+end