Introduction to Electric Circuits

142 Nodal and mesh analysis

1 0

3

6

0

A row matrix

A row matrix has only one row. Thus [X

A row matrix is also called a row vector.

Y Z] is a three-column row matrix.

A column matrix

A column matrix has only one column. Thus

1

2

is a four-row column matrix. A column matrix is also called a column vector.

Matrix addition and subtraction

This is only possible for matrices of the same order and is carried out by adding
or subtracting corresponding elements of the matrices being added or sub-
tracted.

Example 7.2

If

A = 6 and B = 3 X 2

2 Y 4 6

obtain (1) A + B, (2) A - B.

Solution
1A+B=

2A-B=

1 I

y (4+3) (6+X) (Z+2) =

+(-Y) (2+4) (-1+6).]

[

Y- (-Y) (2-4) (-1-6 Y

,]

(6+X) (Z+2)1

(^6 5 3)
(6-X) -2 (Z 272)]
Note that A + B = B + A so that the process is commutative. It is also
associative, so that for the addition of three matrices A, B and C,
A + (B + C) - (A + B) + C.