No convergence at x0
in [Matlab]
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From: farhan sheikh on 12 Nov 2009 01:12 Dear Fellows Hello I am Farhan, presently undergoing thesis phase of my MS. I am using “Matcont” for my thesis. I am facing some problems regarding matcont. I am using an 11th order system. The problem starts when I try to start “Continuation”. Matcont gives me the message “No convergence at x0”. I have confirmed that the initial conditions input in the “Starter” window really correspond to an equilibrium condition. I have confirmed it in the following 02 ways: (a) I have found the derivatives, and these are really zero i.e. my chosen equilibrium point is an equilibrium point in real terms. (b) Time based simulations starting from the chosen equilibrium point converge in an ideal manner. I am interested to know that what else may be the reason for the error message “No convergence at x0”. I have chosen to calculate all derivatives numerically in the system definition window. I have already played with the different tolerance values in the “Continuer” window, and chosen different integration methods like ode45, ode23s etc. but the problem still persists. As till the time I don’t kill this problem, I can’t start with the ‘Continuation’. I am really desperate about this problem. If someone may guide me in this issue, I would be highly obliged. Thanks a lot Best regards Farhan
From: luca mariani on 2 Dec 2009 04:08 Hi farhan, I just started to deal with matcont, and I am also facing the same problem you had. My system is in the steady state, but when I try to continue the equilibrium curve in function of a parameter, it says "no convergence at x0". Did you find the reason (and eventually a solution) for this problem? Many thanks, I am really looking forward to reading your answer All the best Luca sheikh" <farhan_islamabad50(a)yahoo.com> wrote in message <hdg8vi$fc6$1(a)fred.mathworks.com>... > Dear Fellows > Hello > I am Farhan, presently undergoing thesis phase of my MS. I am using “Matcont” for my thesis. > I am facing some problems regarding matcont. I am using an 11th order system. The problem starts when I try to start “Continuation”. Matcont gives me the message “No convergence at x0”. I have confirmed that the initial conditions input in the “Starter” window really correspond to an equilibrium condition. I have confirmed it in the following 02 ways: > > (a) I have found the derivatives, and these are really zero i.e. my chosen equilibrium point is an equilibrium point in real terms. > (b) Time based simulations starting from the chosen equilibrium point converge in an ideal manner. > > I am interested to know that what else may be the reason for the error message “No convergence at x0”. I have chosen to calculate all derivatives numerically in the system definition window. I have already played with the different tolerance values in the “Continuer” window, and chosen different integration methods like ode45, ode23s etc. but the problem still persists. > As till the time I don’t kill this problem, I can’t start with the ‘Continuation’. I am really desperate about this problem. If someone may guide me in this issue, I would be highly obliged. > Thanks a lot > Best regards > Farhan
From: farhan sheikh on 3 Dec 2009 00:30 Dear Luca Hi I am still on my way to resolve this issue and looking forward to others views to get out of it. I intend to do the following if it works: (a) playing with the initial and minimum step sizes. (b) i have chosen "numerically" in the systems windows. I intend to change to calculate 1st, 2nd and 3rd derivatives "symbolically" if it works. (c) Finally, I plan to run my files on some other PC with different Matlab version and windows OS. Lets see. Meanwhile if you get some solution, Plz let me know. Regards "luca mariani" <luca.mariani(a)ifom-ieo-campus.it> wrote in message <hf5api$13a$1(a)fred.mathworks.com>... > Hi farhan, > > I just started to deal with matcont, and I am also facing the same problem you had. > My system is in the steady state, but when I try to continue the equilibrium curve in function of a parameter, it says "no convergence at x0". > Did you find the reason (and eventually a solution) for this problem? > > Many thanks, I am really looking forward to reading your answer > All the best > Luca > > > sheikh" <farhan_islamabad50(a)yahoo.com> wrote in message <hdg8vi$fc6$1(a)fred.mathworks.com>... > > Dear Fellows > > Hello > > I am Farhan, presently undergoing thesis phase of my MS. I am using “Matcont” for my thesis. > > I am facing some problems regarding matcont. I am using an 11th order system. The problem starts when I try to start “Continuation”. Matcont gives me the message “No convergence at x0”. I have confirmed that the initial conditions input in the “Starter” window really correspond to an equilibrium condition. I have confirmed it in the following 02 ways: > > > > (a) I have found the derivatives, and these are really zero i.e. my chosen equilibrium point is an equilibrium point in real terms. > > (b) Time based simulations starting from the chosen equilibrium point converge in an ideal manner. > > > > I am interested to know that what else may be the reason for the error message “No convergence at x0”. I have chosen to calculate all derivatives numerically in the system definition window. I have already played with the different tolerance values in the “Continuer” window, and chosen different integration methods like ode45, ode23s etc. but the problem still persists. > > As till the time I don’t kill this problem, I can’t start with the ‘Continuation’. I am really desperate about this problem. If someone may guide me in this issue, I would be highly obliged. > > Thanks a lot > > Best regards > > Farhan
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