  The two-by-two scattering matrix for one-dimensional scattering processes is
a three-parameter Sp(2) matrix or its unitary equivalent. For one-dimensional
crystals, it would be repeated applications of this matrix. The problem is how
to calculate N repeated multiplications of this matrix. It is shown that the
original Sp(2) matrix can be written as a similarity transformation of Wigner's
little group matrix which can be diagonalized. It is then possible to calculate
the repeated applications of the original Sp(2) matrix.
