What is the Purpose of a Matrix?
Date: 11/04/2003 at 11:12:16 From: Jamie Subject: What exactly is the purpose of a matrix Could you explain to me the exact purpose of a matrix? I can do matrix math, but I'm confused about what they do and what they are for.
Date: 11/04/2003 at 12:08:41 From: Doctor Ian Subject: Re: What exactly is the purpose of a matrix Hi Jamie, A matrix is just a compact notation, which allows you to specify several linear equations at once without having to write them all out. For example, instead of writing 3x + 4y + 5z = 7 2x - 3y + 6z = 6 2x + 5y - 9z = 11 I can write the same thing more compactly using matrices: | 3 4 5 | | x | | 7 | | 2 -3 6 | | y | = | 6 | | 2 5 -9 | | z | | 11 | For a system this small, the savings in effort isn't so great. But the more equations and unknowns you get, the easier it becomes to deal with matrices, instead of with the equations directly. Of course, as with all notations, once it's in place, people figure out how to do new and interesting things with it, which wouldn't have occurred to anyone before the notation was created. That's certainly the case with linear algebra. But the basic idea is just capturing the parallelism in a set of similar-looking equations. It's not unlike what we do when we collapse a set of sentences like Pat, who is 47 years old, makes $38,000 per year as a manager. Chris, who is 29 years old, makes $110,000 per year a stock analyst. Sandy, who is 11 years old, makes $58 per year selling cookies. into a table, Name Age Earnings Occupation ---- --- -------- ---------- Pat 47 38,000 Manager Chris 29 110,000 Stock analyst Sandy 11 58 Cookie salesman The compactness reduces the amount of writing (or typing) that we have to do, but it also makes similarities, differences, and patterns easier to spot by eliminating redundant information (i.e., information that shows up in each equation/sentence without really adding anything new). Does this help? - Doctor Ian, The Math Forum http://mathforum.org/dr.math/
Search the Dr. Math Library:
Ask Dr. MathTM
© 1994- The Math Forum at NCTM. All rights reserved.