The trace of an Square Matrix A is defined by
The trace of a product of square matrices is independent of the order of the multiplication since
The value of the trace can be found using the fact that the matrix can always be transformed to a coordinate system where the
z-Axis lies along the axis of rotation. In the new coordinate system, the Matrix is
Lang, S. Linear Algebra, 3rd ed. New York: Springer-Verlag, pp. 40 and 64, 1987.
© 1996-9 Eric W. Weisstein