text: #ifndef TH_GENERIC_FILE
  #define TH_GENERIC_FILE "generic/SmoothL1Criterion.c"
  #else
  
  void THNN_(SmoothL1Criterion_updateOutput)(
            THNNState *state,
            THTensor *input,
            THTensor *target,
            THTensor *output,
            bool sizeAverage)
  {
    THNN_CHECK_NELEMENT(input, target);
    THNN_CHECK_DIM_SIZE(output, 1, 0, 1);
  
    real sum = 0;
    TH_TENSOR_APPLY2(real, input, real, target,
      real z = fabs(*input_data - *target_data);
      sum += z < 1 ? 0.5*z*z : z - 0.5;
    );
  
    if (sizeAverage)
      sum /= THTensor_(nElement)(input);
  
    THTensor_(set1d)(output, 0, sum);
  }
  
  void THNN_(SmoothL1Criterion_updateGradInput)(
            THNNState *state,
            THTensor *input,
            THTensor *target,
            THTensor *gradInput,
            bool sizeAverage)
  {
    THNN_CHECK_NELEMENT(input, target);
    real norm = (sizeAverage ? 1./((real)THTensor_(nElement)(input)) : 1.);
  
    THTensor_(resizeAs)(gradInput, input);
    TH_TENSOR_APPLY3(real, gradInput, real, input, real, target,
      real x = *input_data - *target_data;
      if (x < -1.)
       *gradInput_data = - norm;
      else if (x > 1.)
       *gradInput_data = norm;
      else
       *gradInput_data = norm * x;
    );
  }
  
  #endif
  