First, save your ‘sae’ function in its own function .m-file called sae.m.
Second, be sure the ode45 call is not within the ODE function, as it seems to be in the code you posted. That creates recursion problems.
Third, comment-out the references to the elements of ‘x’ in ‘sae’. Keep them for information, but be sure they don’t execute.
In sae.m:
function dx=sae(t,x)
% x(1) = x;
% x(2) = y;
% x(3) = z;
dx=zeros(3,1);
dx(1)=10*(x(2)-x(1));
dx(2)=(28*x(1))-x(2)-(x(1)*x(3));
dx(3)=(x(1)*x(2))-((8/3)*x(3));
end
In your script file:
[T,X]=ode45(@sae,[0 20],[0 1 0]);
plot(T,X(:,1),T,X(:,2),T,X(:,3))
legend('x','y','z')
This works, and produces an interesting plot.
