中文说明：复化三点Gauss-lengend公式求pi，计算多重分形非趋势波动分析，对于初学matlab的同学会有帮助，基于SVPWM的三电平逆变的matlab仿真，对信号进行频谱分析及滤波，主要是基于mtlab的程序。
English Description：
Complex three Gauss-lengend formula for PI, the calculation of the multi fractal detrended fluctuation analysis, for the beginner will help matlab students. Based on three-level inverter SVPWM matlab simulation, the signal of frequency spectrum analysis and filtering, and is mainly based on MTLAB procedures.