Time response of modes to an impulse

Hi.

For a 4x4 plant matrix, I want to see the time response of short period mode and phugoid mode of an aircraft for an initial perturbation, respectively. I have 2 roots of the plant matrix for both short period mode and phugoid mode and corresponding period times. How can I plot the responses of the 4 variables with specified initial conditions for an elevator angle deflection?

Thanks.