# What is the mathematical part called in, e.g. "a 5 × 3 matrix"?

I know a 5 × 3 matrix is read a five by three matrix. But, what is the mathematical part (5 × 3) called? A mathematical expression?

• Can you please provide more context? For example, in what kind of sentence are you trying to use the general term for 5x3? Commented May 31, 2018 at 17:36
• In this context 5x3 is the dimensions of the matrix. Commented May 31, 2018 at 17:36
• @Andrew E.g.: "It is noticeable that in translating the noun phrase a 5 × 3 matrix into Persian, proper attention has been paid to the importance of the order of the numbers in a mathematical expression."
– Juya
Commented May 31, 2018 at 17:40
• @Juya expression is a general term and kinda works here, but an expression usually defines a relationship of some kind, e.g. a^2 + b^2 = c^2. So it depends if you're talking specifically about a particular matrix definition or about math in general. I'm curious, though, if you swap the numbers in Persian. That would be confusing. Commented May 31, 2018 at 17:50
• @Andrew If we change the order of the numbers the meaning changes in Persian just as it does in English. The first number refers to the rows and the second number to the columns of a given matrix.
– Juya
Commented May 31, 2018 at 18:00

## 1 Answer

Based on comments on original question:

## Short answer

dimensional expression

## Explanation

A mathematical expression can be considered a "phrase" consisting of more than one "term": https://math.stackexchange.com/questions/2737525/more-formal-definitions-for-equation-expression-term . So "expression" can be used to describe "5x3"

However, "mathematical" is too broad here, especially because "mathematical" can apply to 5x3, but math also applies to matrices, so a qualifier here would be good.

To further narrow down "mathematical", I chose "dimensional", because as @Andrew mentioned, "5x3" defines the dimensions of the matrix.

• I agree that expression works by itself but it seems imprecise for this context. I like your answer of dimensional expression, although expression of the dimensions of the matrix sounds better to me. But then you might as well just say dimensions since, if you're talking about matrices, everyone already knows what you mean. Commented May 31, 2018 at 21:23