Matlab Adding two transfer functions

Question

I'm trying to add two transfer functions together, for example:

tf1=tf(1,[1 0]);  
tf2=tf(2,[1 0]);  
tsum=tf1+tf2

MATLAB considers tf1 and tf2 as blocks connected in series and therefore multiplies tf1 and tf2 together, the result is:

tsum =

3 s
---
s^2

Continuous-time transfer function.

how can I get MATLAB to return the sum of tf1 and tf2 ? so the transfer function that i'm looking for is:

3
-
s

You are looking for parallel combination, so use `parallel(tf1,tf2)` — Autonomous, Mar 16 '13 at 00:04
For those of you trying this at home: remember these functions are part of the Control System Toolbox and are not part of basic Matlab. — Ryan Edwards, Mar 16 '13 at 00:10

score 1 · Accepted Answer · answered Mar 15 '13 at 23:42

1

EDU>> minreal(tsum)

ans =

  3
  -
  s

Continuous-time transfer function.

see

answered Mar 15 '13 at 23:42

Nasser

1 Answers1