function [uv] = w08drift_ode(t,z)
%  w08drift_ode.m  ODE file defining the velocities for w08drift.m
%  current version: djm (23 feb 2004)

global H K sp
  
x = real(z);
y = imag(z);

u = -        H*abs(K)*sp* exp(abs(K)*y) .* cos(K*(x+sp*t));
v = -sign(K)*H*abs(K)*sp* exp(abs(K)*y) .* sin(K*(x+sp*t));

uv = u + i*v;

