Matrices: Lecture Notes | CISC 2210

Special Matrices

A row vector (also called a row matrix) is a matrix of the size $1 \times n$.
- 'Vector' is a synonym of 'array'.
- The number $n$ in a $1 \times n$ row vector is called the vector size and stands for the number of elements in the vector.
- Every $n \times m$ matrix consists of at least one row vector.
- We denote a row vector using a lowercase letter, (usually 'v' for vector) as follows: $\vec{v}$ (
```
$\vec{v}$
```
  ) or $\textbf{v}$ (
```
$\textbf{v}$
```
  ), usually with a subscript, like $\vec{v}_1$ (
```
$\vec{v}_1$
```
  ) to tell what matrix row it corresponds to or just to keep stack of vectors we are working with.
  - Note: In our vector notation, the subscript isn't the vector size: it is just some serial number.
Examples:

19. $I_1 = \vec{v}_1 = \begin{bmatrix} 1 \end{bmatrix}$

7. $A = \vec{v}_2 = \begin{bmatrix} \text{Foo} & \text{Bar} & \text{Baz} \end{bmatrix}$

5. $T = \vec{v}_3 = \begin{bmatrix} 65.7 & 62.4 & 73.8 & 76.6 & 75.0 \end{bmatrix}$