How to solve this system of ODE's

Hi i have a rather simple question, I need to solve a system of ode's of the form Ax = b with given A and timespan and interval.

A = [-199 -198; 99 98]

To solve this i wrote the following code:

function dxdt = System()
dxdt = zeros (2,2);

dxdt(1) = -199*x(1) - 198*x(2);
dxdt(2) = 99*x(1) + 98*x(2);
dxdt = dxdt';
end

And:

[t,x] = ode45(@System, [0 2.5], [1 1])
plot(t,x)

The error that i get is:

Error using System

Too many input arguments

Does someone see where i went wrong?

Answer 1

[Star Strider]

Your ODE funciton has to have your independent and dependent variables (here ‘t’ and ‘x’) as arguments.

Try this:

function dxdt = System(t,x)
dxdt = zeros (2,1);
dxdt(1) = -199*x(1) - 198*x(2);
dxdt(2) = 99*x(1) + 98*x(2);
end

[t,x] = ode45(@System, [0 2.5], [1 1]);
plot(t,x)

[Danny Helwegen]

Thanks, I completly forgot about them

[Star Strider]

As always, my pleasure.