Optimizing parameters for the solution to a system of differential equations

I would like to optimize the parameters a(1) and a(2), but my experimental data is for my y(2) function only.

.m:

function dy = runadj(a,t,y)
dy(1) = -a(1)*y(1)*y(2);
dy(2) = a(1)*y(1)*y(2)-a(2)*y(2);
dy(3) = a(2)*y(2);

Is there a way to optimize these parameters only using experimental data for one equation?

[Torsten]

Of course. Take the simulated values from equation 2 and compare with your experimental values by minimizing the sum of squared differences.

Best wishes

Torsten.