How to use ode45 to solve a system with many dimensions?

Hi there,

I meet a interesting question——How to simulate a system with 100 dimensions using ode45?

Obviously, it's impossible to write all equations as below:

dx(1)=x(1)*(α(1)-a(1,1)*x(1)-a(1,2)*x(2)...)

dx(2)=x(2)*(α(2)-a(2,1)*x(1)-a(2,2)*x(2)...)

...

dx(100)=x(100)*(α(100)-a(100,1)*x(1)-a(100,2)*x(2)...)

Does there exist any tricks to solve this questions?

Looking forward to any suggestions~

Answer 1

[James Tursa]

If I understand your equations correctly, simply

dx = x .* (alpha - a*x);

[Choszit Lee]

Thank you for your answer~Yesterday I have tried to generate a function as below:

function dxdt = MyFunc(t,x)

global a alpha

dxdt = x.*(alpha-a*x);

end

Then run ode45(MyFunc, [0 100], [2 1]) in my main function, I gain a error: Not enough input arguments. However, when I use dxdt=@(t,x)[x.*(alpha-a*x)] instead, it works well...This really puzzles me.

[Walter Roberson]

An error like that can be caused by using

ode45(MyFunc, .....)

instead of

ode45(@MyFunc, .....)