Download 4.1 Organizing Data Into Matrices 4.1

Section 4-1
Organizing Data Into
Matrices
A matrix (plural matrices) is a
rectangular array of numbers
written within brackets.
 A matrix is represented by a
capital letter and classified by its
dimensions.
 The number of horizontal rows and
vertical columns determine the
dimension of a matrix.

3 columns
2 6 4 
A

1 0 8
2 rows
Matrix A is a 2 x 3 matrix.
Example 1 :Write the dimensions of each
matrix.
a.


 4 1 5 


7
0

3


1

10 23

2

3 rows x 3 columns
b.
5 8 0 
1 row x 3 columns
c.
 2 



1


 2 


3


0.8
4 rows x 1 column
Each number in a matrix is a
matrix element.
 A matrix element is identified by
its position within the matrix.
 A lowercase letter with subscripts
is used to name the element
 The subscripts represent the
element’s row number and column
number.

Example 2: Identify element b13 in matrix
B below.
 4
2 0 


B  0.25 8 10 
 1.4 3 1 
Element b13 is 0.
Use matrix B to identify each matrix
element.
-1
a.
b33
b.
b21
0.25
c.
b12
-2
 4
2 0 


B  0.25 8 10 
 1.4 3 1 
Data can be organized in a
matrix to make it easier
to interpret.
Ex 3
Three students kept track of the games
they won and lost in a chess
competition. They showed their results
in a chart. Write a 2 x 3 matrix to show
the data.
Ed
Jo
Y
N
Y
Y
N
Y
Y
Y
Y
Y
Y
N
Y
Y
Lew N Y
Y = win
N
N
Y
Y
N
N = loss
Ed Jo Lew
5

Loss 2

Wins
6
3
1
4



Example 4
On the next slide is the table
that shows the scores from the
2004 Olympics in Athens,
Greece.
Write a matrix W to represent
the information. Use a 4 x 4
matrix.
Floor
Exercise
Vault
Balance
Beam
Uneven
Bars
9.525
9.337
9.350
9.487
Courtney
Kupets
9.400
9.350
9.550
9.637
Courtney
McCool
9.250
9.350
9.112
9.575
9.500
9.512
9.725
9.600
Gymnast
Mohini
Bhardwaj
Carly
Patterson
Mohini
Bhardwaj
Courtney
Kupets
Courtney
McCool
Carly
Patterson
Floor
Exercises
Vault
Balance Uneven
Bars
Beam
9.525
9.337
9.350
9.487
9.400
9.350
9.550
9.637
9.250
9.350
9.112
9.575
9.500
9.512
9.725
9.600












Which element represents Courtney
McCool’s score on the vault?
w32