A Linear Transformation of period two. Since a Linear Transformation has the form,
(1) |
(2) |
(3) |
(4) | |||
(5) | |||
(6) |
(7) |
See also Cross-Ratio, Involution (Line)
References
Woods, F. S. Higher Geometry: An Introduction to Advanced Methods in Analytic Geometry. New York: Dover, pp. 14-15, 1961.