矩阵与方程组的英文版 Probably the most important problem in mathematics is that of solving a system of linear equations. Well over 75 percent of all mathematical problems encoun¬tered in scientific or industrial applications involve solving a linear system at
2.3 Elimination Using Matrices – 用矩阵来消元
用矩阵来消元，我们需要用到消元矩阵，一种可以阐述消元步骤的方式
比如从ithi^{th}ith式减去jthj^{th}jth式的lijl_{ij}lij倍，这样的消元矩阵为EijE_{ij}Eij，所有这样的矩阵组合为E
相似的，可以把所有逆Eij−1E_{ij}^{-1}Eij−1组合为一个总的L=E−1\mathbf{L=E^{-1}}L=E−1
Matrices times Vectors and Ax
