woquanbaobao的博客

从一个例子讲起：2个方程，2个未知数的方程组{2x−y=0−x+2y=3\left\{\begin{aligned}2x-y=0\\-x+2y=3\\\end{aligned}\right.{2x−y=0−x+2y=3​写成矩阵形式为[2−1−12][xy]=[03]\begin{bmatrix}2&-1\\-1&2\end{bmatrix}\...

消元法有方程组{x+2y+z=23x+8y+z=124y+z=2\left\{\begin{aligned}x+2y+z=2\\3x+8y+z=12\\4y+z=2\end{aligned}\right.⎩⎪⎨⎪⎧​x+2y+z=23x+8y+z=124y+z=2​，写成矩阵形式Ax=bAx=bAx=b为[121381041][xyz]=[2122]\begin{bmatrix}1&am...

矩阵乘法法一：假设AAA是m×nm×nm×n矩阵，BBB是n×pn×pn×p矩阵，AB=CAB=CAB=C，则cij=ai1b1j+ai2b2j+⋯+ainbnj=∑k=1naikbkjc_{ij}=a_{i1}b_{1j}+a_{i2}b_{2j}+\cdots+a_{in}b_{nj}=\sum_{k=1}^na_{ik}b_{kj}cij​=ai1​b1j​+ai2​b2j​+⋯+ain...