说明：  用Burg算法估计AR模型参数，进而实现功率谱估计. 形参说明： x——双精度实型一维数组，长度为n，存放随机序列。 n--整型变量,随机序列的长度。 p--整型变量,AR模型的阶数。 a--双精度实型一维数组，长度为(p十1)。存放AR模型的系数a(0),a(1),...,a(p)。 v--双精度实型指针,它指向预测误差功率，即AR模型激励白噪声的方差。
(with Burg algorithm estimates AR model parameters, thereby realizing the power spectrum estimation.- Participation : x-- double-precision real one-dimensional arrays, length n, storage random sequence. N-- integer variables, random sequence length. P-- integer variables, AR model of order. A-- double-precision real one-dimensional arrays, length (p 10). AR storage coefficient of a model (0), a (1 ),..., a (p). V-- double precision real-pointer, it forecast errors at power, AR model that inspired the white noise variance.)