function dy = lotkavolterra2(t,y)

global A a b c d e V k m n;
dy = zeros(2,1);    % a column vector
dy(1) = y(1)*(-e+1/(1+y(1)))- b*y(1)*y(2)/(k+y(1));
dy(2) = c*y(1)*y(2)/(y(1)*y(2)+1) - d*y(2);
% dy(1) = a*y(1)/(A+y(1))-b*y(1)*y(2);
% dy(2) = c*y(1)*y(2)- d*y(2);
% dy(1) = a*y(1)-b*y(1)*y(2);
% dy(2) = c*y(1)*y(2)- d*y(2);