一个FFT类以及一个复数类，实现了快速傅里叶变换及其反变换（FFT和IFFT）以及复数的运算。综合考虑各细节使碟形算法达到最高的效率。-An FFT class as well as a complex and realizes the fast Fourier transform and its inverse transform (FFT and IFFT) and a plurality of computing. Considering all details of the dish a