ode45 where odefun requires more parameters

My odefun.m has the following input structure:

function dy = odefun(t,y,a,b,c)

I want to use ode45 to integrate the ODE, but I need to see an example where the odefun takes in more than just t & y.

Please bear in mind that I've already read the following, and many more:

1. http://www.mathworks.com/help/matlab/math/ordinary-differential-equations.html

2. http://www.mathworks.com/help/matlab/ref/ode45.html

3. http://stackoverflow.com/questions/14943044/passing-additional-arguments-through-function-handle-in-matlab

4. http://stackoverflow.com/questions/1607621/matlab-passing-a-function-handle-parameter-into-another-function-as-a-handle

5. http://www.mathworks.com/help/matlab/matlab_prog/applications-of-function-handles.html

6. http://www.mathworks.com/matlabcentral/answers/160512-error-message-for-ode45-too-many-input-arguments

7. http://www.mathworks.com/matlabcentral/answers/33581-too-many-input-arguments

8. http://www.mathworks.com/matlabcentral/answers/47623-bugfixing-for-ode45-too-many-input-arguments

I've also read about arguments for function handles, "anonymous functions" and much more.

I believe that now it would be most constructive if someone could please just provide an example.

Answer 1

[Star Strider]

I’m not exactly certain what you’re actually asking, since my interpretation of your question is covered in the ode45 documentation. You haven’t listed the code for your ‘odefun’, or described what you want to do, so I’m guessing here.

If I understand correctly, what you want to do is a common way of passing extra parameters to your ODE function.

To use it with ode45, you only pass the ODE solver the ‘t’ and ‘y’ variables:

[t,y] = ode45(@(t,y) odefun(t,y,a,b,c), tspan, ic);

Note that ‘a’, ‘b’, and ‘c’ have to exist in your workspace.

[Jordan Bai]

Thanks, I've been looking for a solution for ages!

Forgive my ignorance, but what exactly does putting @(t,y) first do?

[Rik]

@(t,y) odefun(t,y,a,b,c)

This creates an anonymous function, with t and y as inputs. The values of the other variables are retrieved when the anonymous function is created:

y=1;
f=@(x) x+y;
y=3;
f(1)

ans = 2

[Star Strider]

Rik — Thank you!