How to Approximate Temperature Distribution Using Matrices - dummies

How to Approximate Temperature Distribution Using Matrices

By Mary Jane Sterling

Finite math starts with the basic mathematical processes and draws in all the applications that make the processes usable in the real world. A valuable tool that you’ll learn about in your finite math course is matrices, which help you to organize your data.

A classic problem that can be handled with matrices involves temperature distribution—how the different temperatures at points on a surface are affected by the temperatures closest to them. This is especially important when you can’t take all the temperature measurements throughout the surface.

Say that you have a large, flat, aluminum roof and want to know the approximate temperatures at different positions on the roof. You can’t go out on the roof (ouch, hot, wobbly), but you can measure along the edges. You also know of a property that says the temperature at a point on the surface is the average of the four closest points on a grid drawn over the surface. The following figure represents the points on your roof.

How hot are the spots on the roof?

The temperature at spot x is the average of the temperatures of the four closest points. To the left, the temperature is 120 degrees; above the point, the temperature is 80 degrees; to the right, it’s y degrees; and below, it’s z degrees. So the temperature at point x is the average of the four measures.


Creating the temperatures at the other three points, you have


Multiplying each equation by 4 and arranging the terms in the same order, you have


Now, solve the system for x, y, z, and w. Using an augmented matrix, you get


You go through the steps to put it in reduced-echelon form and get


So the temperature at x = 98.75, at y = 91.25, at z = 103.75, and at w = 96.25 degrees, as shown here.

The average temperatures on the roof.