Alois Steindl

Dear Hil and colleagues, I observe a new phenomenon, which I didn't encounter earlier: I want to draw a bifurcation diagram with steady solutions and periodic orbits. As soon as I select to draw the maximum value of a state variable along a periodic branch, the stationary solutions vanish from the figure and I obtain messages like plotDiagram: solution rejected, invalid layout (LP_LP(1).mat). If you need some test data, I could provide these. With kind wishes Alois

Dear Hil and colleagues, with an example, that I wanted to present in the lecture, I observe a bad error in MatCont 7.6: For a triple pendulum with follower force loading and a supporting spring I follow a branch of Hopf points in the parameter plane and encounter also ZH points. Quite regularly I obtain the error message, that an unexpeted error occured caused by missing/wrong indices. The same problem occurs also, when I follow the zero eigenvalue and encounter the ZH point. The reason for this...

Hello, your equation for y8 looks somewhat strange, I guess you forgot some *-signs. What are dy1 and dy2? Are you looking for steady states? If the problem occurs for y1 and y8, it should be easy to find the corresponding stationary solutions from the y1-y6-equilibria., because y7 and y8 do not appear in these equations. You could also solve these 2 equations separately. Good luck Alois

Frequently matcont starts far away from the initial guess. but usually continuation helps to reach the desired range. I guess this is related to the implemented algorithm for creating the first solution. and sometimes it occurs, when the parameter values are changed a little bit.

You could set the damping and the excitation to zero and look for periodic solutions of the remaining autonomous, conservative system. Since the system is conservative, the periodic solutions will be neutrally stable.

Hello,. why do you think there should be a LP point? Just follow your branches and see, what happens. These need not be connected. What happens to the left of the second curve? I can only second Hil's response: The authors of MatCont cannot solve the users' problems, If you need help, you should take significantly more effort to explain your model and your efforts so far; in your case also the reasoning for your expectations. Kind regards Alois Steindl

Hello, it seems that your matcont system is in some strange state. Try to call matcont clean or matcont clean reset as proposed right at the start of matcont.m Good luck Alois

Hello, your question is quite unspecific. I have no idea what you are trying to do. What happens at the Hopf bifurcation, do you have several pairs of imaginary eigenvalues? In that case it might be necessary to treat an imperfect system, where the Hopf bifurcation points are separated (one critical pair at a HBP). But that is just a wild guess based on your question.