Definition:Matrix/Order
Definition
Let $\sqbrk a_{m n}$ be an $m \times n$ matrix.
Then the parameters $m$ and $n$ are known as the order of the matrix.
Square Matrix
Let $\mathbf A$ be an $n \times n$ square matrix.
That is, let $\mathbf A$ have $n$ rows (and by definition $n$ columns).
Then the order of $\mathbf A$ is defined as being $n$.
Column Matrix
Let $\mathbf A$ be an $n \times 1$ column matrix.
Then the order of $\mathbf A$ is defined as being $n$.
Row Matrix
Let $\mathbf A$ be a $1 \times n$ row matrix.
Then the order of $\mathbf A$ is defined as being $n$.
Also known as
The order of a matrix can also be referred to as its dimensions, but the term dimension has a different, deeper meaning in linear algebra and this may be a source of confusion.
Some sources refer to the size rather than order, which is acceptable enough.
Others use the term type, but this word can have different connotations.
Some sources do not bother to give the order an actual name, merely referring to, say, an $n \times m$ matrix.
Also see
- Results about orders of matrices can be found here.
Sources
- 1954: A.C. Aitken: Determinants and Matrices (8th ed.) ... (previous) ... (next): Chapter $\text I$: Definitions and Fundamental Operations of Matrices: $3$. The Notation of Matrices
- 1998: David Nelson: The Penguin Dictionary of Mathematics (2nd ed.) ... (previous) ... (next): dimension: 2.
- 1998: David Nelson: The Penguin Dictionary of Mathematics (2nd ed.) ... (previous) ... (next): matrix (plural matrices)
- 1998: David Nelson: The Penguin Dictionary of Mathematics (2nd ed.) ... (previous) ... (next): order: 8. (of a matrix)
- 2008: David Nelson: The Penguin Dictionary of Mathematics (4th ed.) ... (previous) ... (next): dimension: 2.
- 2008: David Nelson: The Penguin Dictionary of Mathematics (4th ed.) ... (previous) ... (next): matrix (plural matrices)
- 2008: David Nelson: The Penguin Dictionary of Mathematics (4th ed.) ... (previous) ... (next): order: 8. (of a matrix)
- 2014: Christopher Clapham and James Nicholson: The Concise Oxford Dictionary of Mathematics (5th ed.) ... (previous) ... (next): order (of a matrix)