1 files changed, 40 insertions, 0 deletions
diff --git a/CosineDistance.lua b/CosineDistance.lua
new file mode 100644
index 0000000..061ff92
--- /dev/null
+++ b/CosineDistance.lua
@@ -0,0 +1,40 @@
+local CosineDistance, parent = torch.class('nn.CosineDistance', 'nn.Module')
+
+function CosineDistance:__init()
+   parent.__init(self)
+   self.gradInput = {torch.Tensor(), torch.Tensor()}
+   self.output=torch.Tensor(1)
+end 
+ 
+function CosineDistance:updateOutput(input)
+   local input1, input2 = input[1], input[2]
+   self.w1 = input1:dot(input2)
+   self.w22 = input1:dot(input1)
+   self.w2 = math.sqrt(self.w22)
+   self.w32 = input2:dot(input2)
+   self.w3 = math.sqrt(self.w32)
+   self.output[1] = self.w1/self.w2/self.w3
+   return self.output
+end
+
+function CosineDistance:updateGradInput(input, gradOutput)
+   local v1  = input[1]
+   local v2  = input[2]
+   local gw1 = input[1].new()
+   local gw2 = input[2].new()
+   gw1:resizeAs(v1) 
+   gw2:resizeAs(v1)
+
+   gw1:zero()
+   gw1:add(1/(self.w2*self.w3), v2)
+   gw1:add(-self.w1/(self.w22*self.w2*self.w3), v1)
+   
+   gw2:zero()
+   gw2:add(1/(self.w2*self.w3), v1)
+   gw2:add(-self.w1/(self.w32*self.w2*self.w3), v2)
+
+   gw1:mul(gradOutput[1])
+   gw2:mul(gradOutput[1])
+   self.gradInput = {gw1, gw2}
+   return self.gradInput
+end