1 files changed, 52 insertions, 0 deletions
diff --git a/nerv/layer/mse.lua b/nerv/layer/mse.lua
new file mode 100644
index 0000000..9a97add
--- /dev/null
+++ b/nerv/layer/mse.lua
@@ -0,0 +1,52 @@
+local MSELayer = nerv.class("nerv.MSELayer", "nerv.Layer")
+
+function MSELayer:__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(2, -1)
+end
+
+function MSELayer:init(batch_size)
+    if self.dim_in[1] ~= self.dim_in[2] then
+        nerv.error("mismatching dimensions of previous network output and labels")
+    end
+    self.scale = 1 / self.dim_in[1]
+    self.total_mse = 0.0
+    self.total_frames = 0
+    self.mse = self.gconf.cumat_type(batch_size, self.dim_in[1])
+    self.mse_sum = self.gconf.cumat_type(batch_size, 1)
+    self.diff = self.mse:create()
+end
+
+function MSELayer:update(bp_err, input, output)
+    -- no params, therefore do nothing
+end
+
+function MSELayer:propagate(input, output)
+    local mse = self.mse
+    local mse_sum = self.mse_sum
+    mse:add(input[1], input[2], 1.0, -1.0)
+    self.diff:copy_fromd(mse)
+    mse:mul_elem(mse, mse)
+    mse_sum:add(mse_sum, mse:rowsum(mse), 0.0, self.scale)
+    if output[1] ~= nil then
+        output[1]:copy_fromd(mse_sum)
+    end
+    self.total_mse = self.total_mse + mse_sum:colsum()[0]
+    self.total_frames = self.total_frames + mse_sum:nrow()
+end
+
+-- NOTE: must call propagate before back_propagate
+function MSELayer:back_propagate(bp_err, next_bp_err, input, output)
+    local nbe = next_bp_err[1]
+    nbe:add(nbe, self.diff, 0.0, 2 * self.scale)
+    if bp_err[1] ~= nil then
+        nbe:scale_rows_by_col(bp_err[1])
+    end
+end
+
+function MSELayer:get_params()
+    return nerv.ParamRepo({})
+end