Substitution to solve Coupled differential equations

Hi,

I have the following types of equations:

Here F is known, so I will get p = g(x(i)) which gives me f(i) as a function of all x(i).

Now I need to solve the following coupled differential equations:

How can I solve this problem in MATLAB? Please help.

[Torsten]

Here F is known, so I will get p = g(x(i)) which gives me f(i) as a function of all x(i).

I don't understand this. Could you clarify ?

[Shubham Agrawal]

Thanks for replying.

I know the numeric value of F, the second equation can be used to get p as a function of all x(i). When I substitute it back in the first equation, I can get f(i) as a function of all x(i). Now I have N diiferential equations which become coupled and can be used to solve for all x(i) as a function of time.

Please let me know if you need more clarification. I can share the equations too.

Thanks.

Answer 1

[Bjorn Gustavsson]

Just look at the examples for ode45 - there should be some example explaining how to write a function

returning dxdt when called. It would be something like this:

function dxdt = myode(t,x)
dxdt = zeros(numel(x),1)
dxdt(1) = f1(x,possibly,other,input,arguments);
dxdt(2) = f2(x,possibly,other,input,arguments);
...
dxdt(numel(x)) = fn(x,possibly,other,input,arguments);
end

HTH