Therefore, the signal characterized with dictionary atoms can be extracted by step by step. In fact, the signal decomposition of MP is
the process of orthogonal projection. And that can ensure the decomposition’s uniqueness of chosen dictionary atoms. Fig. 4 shows the process of signal decomposition. From the process of decomposition based on MP, it is known that decomposing every times signal or residual signal must select the atom form over-completed dictionary, calculate and obtain the maximum value. In other words, every step of the calculation should be done based on Eq. (3) and changed to the multiple inner product calculation in a high-dimensional. Ref. [11], so this is the main reason that amount of calculation of signal decomposition is large. If take Eq. (3) as objective optimization function and use DEPSO algorithm, the amount of calculation will be dropped down obviously.