% Brusselator vector field (System 1.8, Kuznetsov, 2nd ed.)

  function v = brusfun(x,a,b) ;
  xdot = a - (b+1)*x(1) + (x(1)^2)*x(2) ;
  ydot = b*x(1) - (x(1)^2)*x(2) ;
  v = [xdot ; ydot] ; 
