1 files changed, 41 insertions, 0 deletions
diff --git a/contrib/lua-torch/nn/L1HingeEmbeddingCriterion.lua b/contrib/lua-torch/nn/L1HingeEmbeddingCriterion.lua
new file mode 100644
index 000000000..6957278f5
--- /dev/null
+++ b/contrib/lua-torch/nn/L1HingeEmbeddingCriterion.lua
@@ -0,0 +1,41 @@
+local L1HingeEmbeddingCriterion, parent = torch.class('nn.L1HingeEmbeddingCriterion', 'nn.Criterion')
+
+function L1HingeEmbeddingCriterion:__init(margin)
+   parent.__init(self)
+   margin = margin or 1
+   self.margin = margin
+   self.gradInput = {torch.Tensor(), torch.Tensor()}
+end
+
+function L1HingeEmbeddingCriterion:updateOutput(input,y)
+   self.output=input[1]:dist(input[2],1);
+   if y == -1 then
+	 self.output = math.max(0,self.margin - self.output);
+   end
+   return self.output
+end
+
+
+local function mathsign(t)
+   if t>0 then return 1; end
+   if t<0 then return -1; end
+   return 2*torch.random(2)-3;
+end
+
+function L1HingeEmbeddingCriterion:updateGradInput(input, y)
+  self.gradInput[1]:resizeAs(input[1])
+  self.gradInput[2]:resizeAs(input[2])
+  self.gradInput[1]:copy(input[1])
+  self.gradInput[1]:add(-1, input[2])
+  local dist = self.gradInput[1]:norm(1);
+  self.gradInput[1]:apply(mathsign)    -- L1 gradient
+  if y == -1 then -- just to avoid a mul by 1
+   if dist > self.margin then
+     self.gradInput[1]:zero()
+   else
+     self.gradInput[1]:mul(-1)
+   end
+  end
+  self.gradInput[2]:zero():add(-1, self.gradInput[1])
+  return self.gradInput
+end