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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?

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
http://mathforum.org/dr.math/

Associated Topics:
High School Linear Algebra

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