说明：  实现矩阵的Cholesky分解,用Cholesky分解求ARMA模型的参数并作谱估计,利用分裂基算法求复序列 的DFT.将得到的 解卷绕，得到无跳变的相频特性.计算七类窗函数并给出归一化对数幅频曲线
(achieve Matrix Cholesky decomposition, Cholesky decomposition used for ARMA model and the parameters for spectral estimation, the use of split-based algorithms for complex sequence of DFT. will be the unwrapped. be no change at the phase frequency characteristics. Calculation seven categories window function is given to one of several pieces of frequency curve)