The algebra of using the 4 × 4 system matrix for astigmatic systems is further simplified by rearranging the system matrix elements, and then dividing the system matrix into four 2 × 2 blocks. The resulting matrix equations have exactly the same algebraic form as the equations for a spherical lens system and the derivations of matrix equations for astigmatic systems become functionally as simple as the derivations for spherical optical systems.
Received April 24, 1981; revision received November 4, 1981.
* Physicist, Ph.D., Member of Faculty, F.A.A.O.
Michael P. Keating
College of Optometry
Ferris State College
Big Rapids, Michigan 49307
© 1982 American Academy of Optometry