<>求解线性方程组

<>右乘向量/矩阵

[ c o l 1 c o l 2 c o l 3 ] [ 3 4 5 ] = [ 3 c o l 1 + 4 c o l 2 + 5 c o l 3 ]
\left[\begin{array}{c} col_{1} & col_{2} & col_{3} \end{array}\right]
\left[\begin{array}{c} 3 \\ 4 \\ 5 \end{array}\right]= \left[\begin{array}{c}
3col_1+4col_2+5col_3 \end{array}\right][col1​​col2​​col3​​] ​345​ ​=[3col1​+4col
2​+5col3​​]

<>左乘向量/矩阵

[ 1 2 7 ] [ r o w 1 r o w 2 r o w 3 ] = [ 1 r o w 1 + 2 r o w 2 + 7 r o w 3 ]
\left[\begin{array}{c} 1 & 2 & 7 \end{array}\right] \left[\begin{array}{c}
row_1 \\ row_2 \\ row_3 \end{array}\right]= \left[\begin{array}{c}
1row_1+2row_2+7row_3 \end{array}\right][1​2​7​] ​row1​row2​row3​​ ​=[1row1​+2row
2​+7row3​​]

<>结果特定行列位置的值

[ r o w 1 r o w 2 r o w 3 ] [ c o l 1 c o l 2 c o l 3 ] = [ r o w 1 c o l 1 r
o w 1 c o l 2 r o w 1 c o l 3 r o w 2 c o l 1 r o w 2 c o l 2 r o w 2 c o l 3 r
o w 3 c o l 1 r o w 3 c o l 2 r o w 3 c o l 3 ] \left[\begin{array}{c} row_1 \\
row_2 \\ row_3 \end{array}\right]\left[\begin{array}{c} col_1 & col_2 & col_3
\end{array}\right] = \left[\begin{array}{c} row_1col_1 & row_1col_2 &
row_1col_3 \\ row_2col_1 & row_2col_2 & row_2col_3 \\ row_3col_1 & row_3col_2 &
row_3col_3 \end{array}\right] ​row1​row2​row3​​ ​[col1​​col2​​col3​​]= ​row1​col
1​row2​col1​row3​col1​​row1​col2​row2​col2​row3​col2​​row1​col3​row2​col3​row3​
col3​​ ​

<>矩阵乘法

AB=C
A是mxn矩阵，
B是nxp矩阵，

<>逆矩阵

<>方阵的逆矩阵

<>求逆矩阵

* 和求解线性方程组一样，一个个求解线性方程组，用消元法慢慢消，然后再回代
* Gauss-Jordan高斯-若尔当消元方法，同时求解多个线性方程组

EA = I 所以E就是A的逆矩阵

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