## 4.2.2 Matrix

A Matrix is used to describe rows and columns. It is delegated by data types Matrix<complex<float> >  type and Matrix<float>  type, which respectively holds complex numbers matrix and real numbers matrix as elements. Below is the definition of Matrix data type. Base Matrix is a class that implements the methods for HARK  .

template<class T> class Matrix :
public BaseMatrix

protected members:
int rows;
int cols;
T *data;


Matrix is generally used for inter-node communication such as MultiFFT  (frequency analysis) and LocalizeMUSIC  (sound source localization). However, in a robot auditory system that uses HARK  for sound source localization, source tracking, separation and speech recognition, an ID is assigned to each sound source in the source tracking process (SourceTracker ). Before this process, Matrix is used for inter-node communication. But, from the source tracking process and beyond, Map  is usually used.