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local PairwiseDistance, parent = torch.class('nn.PairwiseDistance', 'nn.Module')
function PairwiseDistance:__init(p)
parent.__init(self)
-- state
self.gradInput = {torch.Tensor(), torch.Tensor()}
self.output = torch.Tensor(1)
self.norm=p
end
function PairwiseDistance:updateOutput(input)
self.output[1]=input[1]:dist(input[2],self.norm);
return self.output
end
local function mathsign(x)
if x==0 then return 2*torch.random(2)-3; end
if x>0 then return 1; else return -1; end
end
function PairwiseDistance:updateGradInput(input, gradOutput)
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])
if self.norm==1 then
self.gradInput[1]:apply(mathsign)
end
self.gradInput[1]:mul(gradOutput[1]);
self.gradInput[2]:zero():add(-1, self.gradInput[1])
return self.gradInput
end
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