define function and use ode45

Hello! Before using the ode45 solver, first I define multiple first differential equation using function.

However, I keep getting error, and do not know why I get.

function dy=transeq5(t,y)
dy=zeros(44,1);
dy(1) = - y(1)*y(5)*y(34) + y(2)*(y(41)+y(24))+ ...
        y(2)*y(4)*y(36)+y(33)*y(2)*y(5)+y(2)*y(3)*y(32);
end

dy represents first derivative of y respect to t. :dy =dy/dt

I declared y values globally.

Also, I wrote dy(2),... upto dy(10). However, I attach partially where I am having troubles.

However, the error messages I receive are:

Not enough input arguments.

and

Error in transeq5 (line 5)
dy(1) = - y(1)*y(5)*y(34) +
y(2)*(y(41)+y(24))+ ...
    

Can you explain?

Later, I am doing:

options=odeset('RelTol',1e-5,'AbsTol',1e-5*ones(44,1));
[T,Y]=ode45(@transeq5,[0 2e-3],y);

Thank you so much!

Answer 1

[Cris LaPierre]

It looks to me like you need to define your initial conditions for y. You say you declare them globally. You do not want to do that.

y0 = rand(1,44);
[T,Y]=ode45(@transeq5,[0 2e-3],y0);

plot(T,Y(:,1))

function dy=transeq5(t,y)
dy=zeros(44,1);
dy(1) = - y(1)*y(5)*y(34) + y(2)*(y(41)+y(24))+ ...
        y(2)*y(4)*y(36)+y(33)*y(2)*y(5)+y(2)*y(3)*y(32);
end