说明：  qr算法的matlab代码，利用矩阵的QR分解，逐步按递推法构造矩阵的分解序列的过程，只要原始矩阵式非奇异矩阵，则由QR算法就完全确定其分解序列了
(qr algorithm matlab code using a QR decomposition of the matrix, step by step process of the recursive method to construct the matrix decomposition sequence, as long as the original matrix nonsingular matrix by the QR algorithm completely determine the sequence of its decomposition)