function dy=roessler(t, y, dummy, p)
% periodic
% a=.2; b=.7; c=3.6;
% chaos (standard)
% a=.2; b=.2; c=5.7;
% a=.1; b=.1; c=9;
% funnel
% a=.2925; b=.1; c=8.5;

dy = zeros(3,1);

if nargin < 3 | isempty(p)
   a = .2;
   b = .2;
   c = 5.7;
else
   a = p(1);
   b = p(2);
   c = p(3);
end

dy(1) = -y(2) - y(3);
dy(2) = y(1) + a * y(2);
dy(3) = b + y(3) * (y(1) - c);