batch_euclidean_vector_layer.cu

#include <algorithm>
#include <vector>

#include "caffe/layers/batch_euclidean_vector_layer.hpp"

namespace caffe {
  template <typename Dtype>
  void BatchEuclideanVectorLayer<Dtype>::Forward_gpu(const vector<Blob<Dtype>*>& bottom, const vector<Blob<Dtype>*>& top){
  	const Dtype* bottom_data1 = bottom[0]->gpu_data();
    const Dtype* bottom_data2 = bottom[1]->gpu_data();
    Dtype* top_data = top[0]->mutable_gpu_data();
    Dtype* diff_feat_data = diff_feat.mutable_gpu_data();

    max_d = Dtype(0.0);
  for (int n = 0; n < num_; ++n){
        //diff_feat = x_n - x_nn
        caffe_gpu_sub(channels_, bottom_data1+n*channels_, bottom_data2+n*channels_, diff_feat_data);
        //sim = diff_feat * diff_feat
        Dtype distance = Dtype(0.0);
        caffe_gpu_dot(channels_, diff_feat_data, diff_feat_data, &distance);
        if (distance > max_d){
          max_d = distance;
        }
        //top[n, nn] = sim
        caffe_gpu_set(1, distance, top_data+n);
    }
    caffe_gpu_scal(num_, Dtype(1.0) / max_d, top_data);  
  }

  template <typename Dtype>
  void BatchEuclideanVectorLayer<Dtype>::Backward_gpu(const vector<Blob<Dtype>*>& top, const vector<bool>& propagate_down, const vector<Blob<Dtype>*>& bottom){
  	if (!propagate_down[0]){return;}
  	const Dtype* top_diff = top[0]->gpu_diff();
  	Dtype* bottom_diff1 = bottom[0]->mutable_gpu_diff();
    Dtype* bottom_diff2 = bottom[1]->mutable_gpu_diff();
  	caffe_gpu_set(num_*channels_, Dtype(0.0), bottom_diff1);
    caffe_gpu_set(num_*channels_, Dtype(0.0), bottom_diff2);
  	Dtype* diff_feat_data = diff_feat.mutable_gpu_data();
  	const Dtype* bottom_data1 = bottom[0]->gpu_data();
    const Dtype* bottom_data2 = bottom[1]->gpu_data();
  	Dtype scale = Dtype(0.0);
    for (int n = 0; n < num_; ++n){
        caffe_gpu_sub(channels_, bottom_data1+n*channels_, bottom_data2+n*channels_, diff_feat_data);
        caffe_copy(1, top_diff+n, &scale);
    //const Dtype* diff_feat_data2 = diff_feat.gpu_data();
        caffe_gpu_axpy(channels_, scale*Dtype(2.0) / max_d, diff_feat_data, bottom_diff1+n*channels_);
        caffe_gpu_axpy(channels_, scale*Dtype(-2.0) / max_d, diff_feat_data, bottom_diff2+n*channels_);
      }
  }
  INSTANTIATE_LAYER_GPU_FUNCS(BatchEuclideanVectorLayer);
}