Fix SparseLinear

Fixed an issue with SparseLinear and added a test along with a new class
SparseJacobian (for testing sparse modules)

1 files changed, 17 insertions, 0 deletions

diff --git a/SparseLinear.lua b/SparseLinear.lua
index f1a2be5..735d0ed 100644
--- a/SparseLinear.lua
+++ b/SparseLinear.lua
@@ -42,3 +42,20 @@ end
 function SparseLinear:accGradParameters(input, gradOutput, scale)
    return input.nn.SparseLinear_accGradParameters(self, input, gradOutput, scale)
 end
+
+function SparseLinear:updateGradInput(input, gradOutput)
+   if self.gradInput then
+      self.gradInput:resize(input:size())
+      self.gradInput:copy(input)
+      local numNonzero = self.gradInput:size(1)
+      for e=1,numNonzero do         
+         local g = 0
+         local i = self.gradInput[{e,1}]
+         for j=1,self.output:size(1) do
+            g = g + self.weight[{j,i}] * gradOutput[j]
+         end
+         self.gradInput[{e,2}] = g
+      end
+      return self.gradInput
+   end
+end
\ No newline at end of file