说明：  程序说明：y = pca(mixedsig)，程序中mixedsig为 n*T 阶混合数据矩阵，n为信号个数，T为采样点数。y为 m*T 阶主分量矩阵。n是维数，T是样本数。
(Procedure Note: y = pca (mixedsig), the program mixedsig for the n* T-order mixed data matrix, n is the signal number, T the sampling points. y for m* T-order principal component matrix. n is the dimension, T is the number of samples.)