“…Complex feature vectors represent periodic/cyclic data, such as oscillation and wave, e.g., electromagnetic phenomena, electric circuits, acoustic/biomedical signals, and imaging radar, in a natural way. Complex valued neural networks (CVNN) have been used for array signal analysis [ 32 , 33 ], radar image processing [ 34 , 35 ], and EEG analysis [ 36 , 37 , 38 ].…”