## 4.2.2 Matrix

Matrix indicates a matrix. The representative types are Matrix<complex<float> >  type and Matrix<float>  type, a matrix of complex numbers and a matrix with real numbers as elements, respectively. Matrix  type is defined as follows. However, Base Matrix  is the class in which FlowDesigner  methods are implemented.

template<class T> class Matrix :
public BaseMatrix

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


The nodes that use Matrix  for inter-node communication include MultiFFT  (frequency analysis) and LocalizeMUSIC  (sound source localization). Further, in a robot audition system with typical functions like sound source location / source tracking / separation and speech recognition for which HARK   is used, an ID is given to each sound source in sound source tracking (SourceTracker ). Matrix  is used for inter-node communication in the processing before an ID is given, and Map  is often used in processing after that.