应用FFT方法计算时间序列平均周期的源码。不是很复杂，不过效果比较好。可供参考-Application of FFT calculated the average cycle time of the source sequence. Not very complicated, but the effect is better. For reference

一个MATLAB的快速付立叶程序，fft计算平均周期-A fast Fourier MATLAB program, fft calculation of the average cycle