Linear Algebra

[Linear Algebra] #04 Inverse Matrix by Gauss-Jordan Elimination

비온다리 2021. 2. 1. 23:44

1. Gauss-Jordan Elimination

 

[ $A$   |   $I$ ] → [ $I$   |  $A^{-1}$b]

 

 

 

2. Elementary matrices and a method for finding  $A^{-1}$

 

Def. Matrices A and B are said to be row-equavalent if either (here each) can be obtained from the other by a squence of elementary row operations.

 

$\widetilde A$ = [ $A$   |   $I$ ] →    ···   → [ $I$   |  $A^{-1}$b]

                            ↘ row-equavalent !

 

 

Def. A matrix E is called an elementary matrix if it can be obtained from an identity matrix by performing a single elementary row operation.

 

[ $A$   |   $I$ ]  →  [ x   |   E1 ]  →  [ x   |   E2 ]  →  [ x   |   E3 ]  →  [ $I$   |  $A^{-1}$b]