Among other unconventional numerical methods, W. Kahan has suggested a discretization of a simple Lotka-Volterra system with the property that the computed points do not spiral. We explain this behaviour by showing that Kahan's method is symplectic with respect to a noncanonical symplectic structure. © 1994.
Sanz-Serna, J. M. (1994). An unconventional symplectic integrator of W. Kahan. Applied Numerical Mathematics, 16(1–2), 245–250. https://doi.org/10.1016/0168-9274(94)00030-1