2 files changed, 39 insertions, 6 deletions
diff --git a/nerv/layer/duplicate.lua b/nerv/layer/duplicate.lua
index 58758e8..fbd4a9e 100644
--- a/nerv/layer/duplicate.lua
+++ b/nerv/layer/duplicate.lua
@@ -16,13 +16,10 @@ function DuplicateLayer:__init(id, global_conf, layer_conf)
     end
 end
 
-function DuplicateLayer:init(batch_size)
+function DuplicateLayer:init()
 end
 
-function DuplicateLayer:batch_resize(batch_size)
-end
-
-function DuplicateLayer:update(bp_err, input, output)
+function DuplicateLayer:batch_resize()
 end
 
 function DuplicateLayer:propagate(input, output)
@@ -32,9 +29,12 @@ function DuplicateLayer:propagate(input, output)
     end
 end
 
-function DuplicateLayer:back_propagate(bp_err, next_bp_err, input, output)
+function DuplicateLayer:back_propagate(bp_err, next_bp_err)
     next_bp_err:copy_from(bp_err[1])
     for i = 2, #self.dim_out do
         next_bp_err:add(next_bp_err, bp_err[i], 1.0, 1.0)
     end
 end
+
+function DuplicateLayer:update()
+end
diff --git a/nerv/layer/identity.lua b/nerv/layer/identity.lua
new file mode 100644
index 0000000..dc796fb
--- /dev/null
+++ b/nerv/layer/identity.lua
@@ -0,0 +1,33 @@
+local IdentityLayer = nerv.class('nerv.IdentityLayer', 'nerv.Layer')
+
+function IdentityLayer:__init(id, global_conf, layer_conf)
+    self.id = id
+    self.dim_in = layer_conf.dim_in
+    self.dim_out = layer_conf.dim_out
+    self.gconf = global_conf
+    self:check_dim_len(1, 1)
+    if self.dim_in[1] ~= self.dim_out[1] then
+        nerv.error('mismatching dimensions of input and output')
+    end
+end
+
+function IdentityLayer:init()
+end
+
+function IdentityLayer:batch_resize()
+end
+
+function IdentityLayer:propagate(input, output)
+    output[1]:copy_from(input[1])
+end
+
+function IdentityLayer:back_propagate(bp_err, next_bp_err)
+    next_bp_err[1]:copy_from(bp_err)
+end
+
+function IdentityLayer:update()
+end
+
+function IdentityLayer:get_params()
+    return nerv.ParamRepo({})
+end