|
Why is he called the
identity?
Remember the multiplicative
identity for regular numbers?
What can you multiply
3 by
so he stays a 3?
1!
 |
AND |
 |
It works both ways!
It's the same for our
identity matrix!
 |
AND |
 |
By the way, this guy
is the 2 x 2
identity:
![I = [ row 1: 1 , 0 row 2: 0 , 1 ]](images/05-matrices-14a.gif)
So, what's the
3 x 3
identity?
![I = [ row 1: 1 , 0 , 0 row 2: 0 , 1 , 0 row 3: 0 , 0 , 1 ]](images/05-matrices-15.gif)
The
4 x 4 identity?
![I = [ row 1: 1 , 0 , 0 , 0 row 2: 0 , 1 , 0 , 0 row 3: 0 , 0 , 1 , 0 row 4: 0 , 0 , 0 , 1 ] ... Get the pattern? ... It's ones down the main diagonal and zeros everywhere else.](images/05-matrices-16.gif)
*All identity
matrices are square.
Continued on the
next
page
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![A = [ row 1: 2 , -6 row 2: -5 , 8 ]](images/05-matrices-11.gif)
![I = [ row 1: 1 , 0 row 2: 0 , 1 ]](images/05-matrices-12.gif)
