Let be the open unit disk, the closed unit disk, and the unit circle.
* The spectrum of is .
* The point spectrum of is empty: .
* The approximate point spectrum of is the unit circle: . (en)
To show , use the matrix representation of , and note that it is bounded iff .
To show , directly show that implies .
To show , note that for any with , so . Conversely, for any , construct the following unit vectorthen , which converges to 0 at . (en)