MIT OpenCourseWare Close Window
 
» Required Reading » Table of Contents » Chapter 32

32.11 Guessing Eigenvectors

Previous Section Next Chapter

Here is a game you can set up on a spreadsheet. Enter an arbitrary matrix M somewhere.
Three by three is a good way to start.
Enter a 3 component column vector v and use the mmult command (or do it out yourself to compute Mv and for each component of v compute the ratio of . Calculate the variance of these ratios (that is, the sum of their squares minus the square of their sum.)
The players can take turns generating the original M and v; then they take turns modifying v by changing one of its components. If the variance of the ratios decreases the player scores a point, otherwise loses one. The game ends when the variance becomes negligible, say less than 10-10.

The ratios then will be more or less the same and hence the eigenvalue associated with the eigenvector produced.

If you get too good at this, you can try with a 5 by 5 matrix, though it is boring to enter one at the start.