On the exponentials of some structured matrices
Viswanath Ramakrishna, Fred M. Costa · Journal of Physics A Mathematical and General · 2004
This paper provides explicit techniques to compute the exponentials of a variety of structured 4 × 4 matrices. The procedures are fully algorithmic and can be used to find the desired exponentials in closed form. With one exception, they require no spectral information about the matrix being exponentiated. They rely on a mixture of Lie theory and one particular Clifford algebra isomorphism. These can be extended, in some cases, to higher dimensions when combined with techniques such as Givens rotations.