How to define simultaneous equations for ODE45

Suppose I have equations

I understand I write

f=@(t,x,a)[x(1)+x(2),x(1)-a*x(2)]

But I hope to define equations one by one f1 and f2 and then combine into f. Please advise.

Answer 1

[madhan ravi]

f1 = @(t,x)  x(1) + x(2)
f2 = @(t,x,a) x(1)-a*x(2)
F = @(t,x,a) [f1(t,x);f2(t,x,a)]

[alpedhuez]

Thank you. Let me work on it.