solving a ODE using ode45 or etc. with certain number of timestepping

4 次查看（过去 30 天）
Hossein
Hossein 2015-6-16
回答： Walter Roberson 2015-6-16
Hi everybody,
I want to solve an ODE using Adams-Bashforth 4th order method which needs the initial values of previous steps so I need to solve the ODE 4 or 5 times using other method such as Runge-Kutta. As far as ode45 is an adaptive time-stepping solver in order to save computation time has anybody any suggestion how can I make solver to do solving for just 4 or 5 times and then break it?
many tnx in advance.

请先登录，再回答此问题。

回答（2 个）

Torsten
Torsten 2015-6-16
Use the Runge-Kutta method to calculate 3 data points in addition to the initial condition:
for i = 1:3
k1 = f(t,y);
k2 = f(t+h/2, y+h/2*k1);
k3 = f(t+h/2, y+h/2*k2);
k4 = f(t+h, y+h*k3);
y = y+h/6*(k1 + 2*k2 + 2*k3 + k4);
t = t + h;
yn(1,i+1) = y;
end
Best wishes
Torsten.
  2 个评论
Hossein
Hossein 2015-6-16
dear torsten tnx for the answer but it can not help me because I prefer using ode45 routin based on some oder problems and complexity and my question refers to adjusting number of steps just in ode45.
Torsten
Torsten 2015-6-16
Well, you can set h, 2*h and 3*h as output times for the solution from ODE45 and feed your Adams routine with these values.
Best wishes
Torsten.

请先登录，再进行评论。

Walter Roberson
Walter Roberson 2015-6-16
Configure an OutputFcn option that tests the number of function calls from the information structure passed in and sets the termination flag appropriately.

类别

在 Help Center 和 File Exchange 中查找有关 Ordinary Differential Equations 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by