function dy = el_nino_de(t,y,params)

% % Lorenz
% if nargin < 3 params= [10 8/3 24]; end
% if nargin < 2 y = zeros(3,1); end
% if nargin < 1 t = 0; end
% 
% params= [10 8/3 28];
% 
% s=params(1);
% b=params(2);
% r=params(3);
% 
% dy = [    s*(y(2)-y(1)) 
%           r*y(1)-y(2)-y(1)*y(3) 
%            -b*y(3)+y(1)*y(2)        
%        ];


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%


% El Nino modell 
%dx = By - C(x + p)
%dy = xz - y
%dz = - xy - z + 1
%B = 102, C = 3, p = 0 in Vallis
%B = 102, C = 3, p = 0.83 in Tung -> aszimmetrikus Lorenz

if nargin < 3; params= [102 3 0.83]; end
if nargin < 2; y = zeros(3,1); end
if nargin < 1; t = 0; end

B=params(1);
C=params(2); 
p=params(3);

dy = [  B*y(2) - C*(y(1) + p)
        y(1)*y(3) - y(2)
        - y(1)*y(2) - y(3) + 1   ];
    