设 A 是n阶方阵，如果存在数m和非零n维列向量 x，使得 Ax=mx 成立，则称 m 是A的一个特征值（characteristic value)或本征值（eigenvalue)。非零n维列向量x称为矩阵A的属于（对应于）特征值m的特征向量或本征向量，简称A的特征向量或A的本征向量。(Let A be a n order square, and if there is a number of M and nonzero n-dimensional column vector x, so that Ax=mx is established, then M is called a A (characteristic, value) or eigenvalue (eigenvalue). The nonzero n-dimensional column vector x is called the characteristic vector or eigenvector of the (corresponding) eigenvalue m of the matrix A, referred to as the eigenvector of A or the eigenvector of A.)