1 files changed, 111 insertions, 0 deletions
diff --git a/generic/LogSoftMax.c b/generic/LogSoftMax.c
new file mode 100644
index 0000000..5d4dbfc
--- /dev/null
+++ b/generic/LogSoftMax.c
@@ -0,0 +1,111 @@
+#ifndef TH_GENERIC_FILE
+#define TH_GENERIC_FILE "generic/LogSoftMax.c"
+#else
+
+static int nn_(LogSoftMax_updateOutput)(lua_State *L)
+{
+  THTensor *input = luaT_checkudata(L, 2, torch_(Tensor_id));
+  THTensor *output = luaT_getfieldcheckudata(L, 1, "output", torch_(Tensor_id));
+  real *input_data, *output_data;
+  long nframe = 0, dim = 0;
+  long t, d;
+
+  if(input->nDimension == 1)
+  {
+    nframe = 1;
+    dim = input->size[0];
+  }
+  else if(input->nDimension == 2)
+  {
+    nframe = input->size[0];
+    dim = input->size[1];
+  }
+  else
+    THArgCheck(0, 2, "vector or matrix expected");
+
+  input = THTensor_(newContiguous)(input);
+  THTensor_(resizeAs)(output, input);
+
+  input_data = THTensor_(data)(input);
+  output_data = THTensor_(data)(output);
+  for(t = 0; t < nframe; t++)
+  {
+    accreal logsum = 0;
+    real maxInput = -THInf;
+
+    for(d = 0; d < dim; d++)
+      maxInput = THMax(maxInput, input_data[d]);
+
+    for(d = 0; d < dim; d++)
+      logsum += THExpMinusApprox(maxInput-input_data[d]);
+    logsum = maxInput + log(logsum);
+
+    for(d = 0; d < dim; d++)
+      output_data[d] = input_data[d] - logsum;
+
+    input_data += dim;
+    output_data += dim;
+  }
+
+  THTensor_(free)(input);
+
+  return 1;
+}
+
+static int nn_(LogSoftMax_updateGradInput)(lua_State *L)
+{
+  THTensor *gradOutput = luaT_checkudata(L, 3, torch_(Tensor_id));
+  THTensor *output = luaT_getfieldcheckudata(L, 1, "output", torch_(Tensor_id));
+  THTensor *gradInput = luaT_getfieldcheckudata(L, 1, "gradInput", torch_(Tensor_id));
+  real *gradInput_data, *gradOutput_data, *output_data;
+  long nframe = 0, dim = 0;
+  long t, d;
+
+  if(output->nDimension == 1)
+  {
+    nframe = 1;
+    dim = output->size[0];
+  }
+  else if(output->nDimension == 2)
+  {
+    nframe = output->size[0];
+    dim = output->size[1];
+  }
+  else
+    THError("vector or matrix expected");
+
+  THTensor_(resizeAs)(gradInput, output);
+  gradInput_data = THTensor_(data)(gradInput);
+  output_data = THTensor_(data)(output);
+  gradOutput_data = THTensor_(data)(gradOutput);
+  for(t = 0; t < nframe; t++)
+  {
+    accreal sum = 0;
+    for(d = 0; d < dim; d++)
+      sum += gradOutput_data[d];
+
+    for(d = 0; d < dim; d++)
+      gradInput_data[d] = gradOutput_data[d] - exp(output_data[d])*sum;
+
+    gradInput_data += dim;
+    output_data += dim;
+    gradOutput_data += dim;
+  }
+
+  return 1;
+}
+
+static const struct luaL_Reg nn_(LogSoftMax__) [] = {
+  {"LogSoftMax_updateOutput", nn_(LogSoftMax_updateOutput)},
+  {"LogSoftMax_updateGradInput", nn_(LogSoftMax_updateGradInput)},
+  {NULL, NULL}
+};
+
+void nn_(LogSoftMax_init)(lua_State *L)
+{
+  luaT_pushmetaclass(L, torch_(Tensor_id));
+  luaT_registeratname(L, nn_(LogSoftMax__), "nn");
+  lua_pop(L,1);
+}
+
+#endif