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Matrix: Why Use m and n?

Date: 09/06/2001 at 22:48:22
From: khalid mahmood
Subject: Order of matrix

Dr. Maths!

W do we use the letters "m" and "n" when we want to represent the 
order of a matrix? And why do we use "x" between them?

Thanks in advance for help.
Khalid Mahmood

Date: 09/07/2001 at 14:42:47
From: Doctor Peterson
Subject: Re: Order of matrix

Hi, Khalid.

As always in algebra, it makes no difference at all what letters you 
use for variables. We just tend to use "n" for simple counts, since it 
reminds us of "number," and "m" is near "n" for use when we need two 
similar counts.

The multiplication sign "x," read in this case as "by," derives from 
its usage in describing the dimensions of a rectangle; the area of an 
"L by W" rectangle is the product LxW, so we use the latter as a 
symbol for the former. And in fact, the number of elements in an 
"m x n" matrix is m*n.

- Doctor Peterson, The Math Forum   
Associated Topics:
High School Linear Algebra

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