Closed-Form Expressions for the Noncompact Part of $Sp(2n)$
  In a comment on the paper of Habib and Ryne, chao-dyn/9406010 and Phys.Rev.Lett. vol.74, 70 (1995), I point out that the Iwasawa decomposition of the symplectic group can be used to write down closed-form expressions for the noncompact part of the group and thus to compute the Lyapunov exponents in systems with more than two degrees of freedom using the cited method. 
Ivan Gjaja