This applet helps you search for real eigenvectors and
eigenvalues of 2x2 matrices.
An eigenvalue/vector is a solution of the equation
A x = k x
where when multiplying a vector x with a matrix A, you want to
know which vectors x will have a transformation Ax that is
just a multiple of x. Typically you find for a given matrix,
that when you have a solution to this, that there is a constant
(or one of a few constant) multiples, or eigenvalues, that will
be allowed. While there are many eigenvectors, you find that they
are all simply multiples of each other, and
there are only as many (and sometimes less) linearly
independent eigenvectors and their associated eigenvalues
as the dimension of the matrix (i.e. a 2x2 matrix will
have no more than 2 eigenvalues and linearly
independent eigenvectors).
Algorithm
For linear transformations, the matrix-vector product A x is
given by