[sci.math] Matrix Properties

bobm@ee.rochester.edu (Bob Molyneaux) (11/29/89)

Hi All,
	A square matrix A is said to be nilpotent if
A^k = 0 for some value of k.

	A square matrix A is said to be idempotent if
A^2 = A ==>  A^k = A for all values of k.

	Is there a classification for the square matrix
A for which A^k = A for not all but some value(s) of k?

	Please email resonses along with references.
(Subject references not yours!)

Thanks

bobm.ee.rochester.edu