Finding overall gain and phase of a system

In a simple way,here is what I intended to do :

 I have got 2 transfer functions G1 and G2. Gn is not a transfer function but has got a gain and a phase.

 s=tf('s')
 G1=1/s;
 G2=5/s^3;
I want to find the overall gain and phase of the system at the frequency w=1. I can get the gain and phase of G1 and G2 at w=1 by:

 [m1,p1]=bode(G1,1)
 [m2,p2]=bode(G2,1)
 m1=1,p1=-90
 m2=5,p2=-270
Assuming my gain at w=1 for Gn is 5 and the phase is -100 degree. How can i find the overall gain and phase of the system at w=1. The closed loop positive feedback is

 Cloop=G1/(1-G1*G2*GN)

 Thanks

 Yash

Answer 1

[Arkadiy Turevskiy]

freq=1;
resp=5*exp(i*2*pi/360*100);
Gn=frd(resp,freq);
[m3,p3]=bode(Gn)

m3 =

    5.0000

p3 =

   100

Cloop=G1/(1-G1*G2*Gn);
[m4,p4]=bode(Cloop,1)
m4 =

    0.0397

p4 =

-12.2403

Answer 2

[yashvin]

Hi Arkadiy,

Thanks for your reply.

But if my phase of Gn is more than 180 or less than -180 degree,

For example taking a phase for Gn to be 200 degree,

freq=1; resp=5*exp(i*2*pi/360*200); Gn=frd(resp,freq); [m3,p3]=bode(Gn)

m=5 but p3=-160.

How can i represent the resp for any magnitude of phase . Phase can Gn can take values of 500 degree or -400.

Is there a necessary way of representing it without losing my phase?

Thanks

Yash