text: #ifndef DESCRIPTOR_PROJECTION_TRAIN_PROJECTION_MATRIX_H_
  #define DESCRIPTOR_PROJECTION_TRAIN_PROJECTION_MATRIX_H_
  namespace vi_map {
  class VIMap;
  }  // namespace vi_map
  
  namespace descriptor_projection {
  void TrainProjectionMatrix(const vi_map::VIMap& map);
  }  // namespace descriptor_projection
  #endif  // DESCRIPTOR_PROJECTION_TRAIN_PROJECTION_MATRIX_H_
  