deltaGi = 420. - 380.; # variation in the without feedback gain
Gi = 400.; # without feedback gain
T = 400.; # transfer function of the closed loop system
# (variation in T)/T = (change in G)/G * (1/ 1+H*G) = 0.02
# 1 + H*G = R
R = (deltaGi/Gi)/0.02;
G = T*R; # new direct transmission gain with feedback
H = (G/T - 1.)/G; # feedback factor
print '%s %.2f' %("new direct transmission gain with feedback = ",G)
print '%s %.2e' %("feedback factors = ",H)