[LONGITUDINAL]
input = {a, b, tau1, tau2}

EQUATION:
t0 = 0
f1_0 = 10+t
f2_0 = 3
ddt_f1 = a*delay(f2,tau2) - b*delay(f1,tau1)
ddt_f2 = b*delay(f1,tau1) - a*delay(f2,tau2)
