1 files changed, 12 insertions, 2 deletions

diff --git a/Narrow.lua b/Narrow.lua
index 0754d45..a6ebaa3 100644
--- a/Narrow.lua
+++ b/Narrow.lua
@@ -16,7 +16,12 @@ function Narrow:updateOutput(input)
    if length < 0 then
       length = input:size(dim) - self.index + self.length + 2
    end
-   local output=input:narrow(dim,self.index,length)
+   local index = self.index
+   if self.index < 0 then
+      index = 1
+      length = input:size(dim) - length
+   end
+   local output=input:narrow(dim, index, length)
    self.output = self.output:typeAs(output)
    self.output:resizeAs(output):copy(output)
    return self.output
@@ -28,8 +33,13 @@ function Narrow:updateGradInput(input, gradOutput)
    if length < 0 then
       length = input:size(dim) - self.index + self.length + 2
    end
+   local index = self.index
+   if self.index < 0 then
+      index = 1
+      length = input:size(dim) - length
+   end
    self.gradInput = self.gradInput:typeAs(input)
    self.gradInput:resizeAs(input):zero()
-   self.gradInput:narrow(dim,self.index,length):copy(gradOutput)
+   self.gradInput:narrow(dim,index,length):copy(gradOutput)
    return self.gradInput
 end