function V = delfi(x,y)

% delfi(X,Y) returns the value of the Delfi potential at (X,Y).

V = 1/4*(x.^2+y.^2).^2+0.54433105395182*x.^3.*(y-1)-y.*(x.^2+y.^2) ...
    +1/2*(x.^2+3*y.^2);
