Numerical integration "backwards" for ODE45

Hi There;

I should apply Backword integration for system of differential equation by ODE45 solver in Matlab, it seems easy for some people, I want an example to understand how to make Backword integration. your answer appreciated.

Best

AA

Answer 1

[Torsten]

fun = @(t,y) y;
tspan = [0 1];
y0 = 1;
[Tf,Yf] = ode45(fun,tspan,y0);
tspan = [1 0];
y0 = exp(1);
[Tb,Yb] = ode45(fun,tspan,y0);
plot(Tf,Yf,Tb,Yb)

[Amirah Algethami]

thanks. more clear for me.

Answer 2

[Fabio Freschi]

you may be interested to read the comments to this post

https://www.mathworks.com/matlabcentral/answers/4592-numerical-integration-backwards

[Amirah Algethami]

yes, I have looked at it before, still confused I want full example. if you could do that !. thanks for replying on me.

Regards;

AA

[Fabio Freschi]

@Torsten already reported an example. I still warn you to pay attention to integrate backwards because in some cases you may have numerica blowup

[Amirah Algethami]

thanks , I hoping that not will happen with my equations.