Why do I get this error?

Any idea of why do I get this error?

>> num = 1

num =

     1

>> denom = [1 2 3]

denom =

     1     2     3

>> sys = tf(num,denom)

sys =

        1
  -------------
  s^2 + 2 s + 3

Continuous-time transfer function.

>> bandwidth(sys) Error using DynamicSystem/bandwidth (line 33) The "bandwidth" command cannot be used for models of class "tf".

Answer 1

[Babak]

Just worked on my computer.. here's your result:

 >>  bandwidth(sys)

 ans =

    2.0385

My ver command gives this:

 >> ver
------------------------------------------------------------------------------------------------
MATLAB Version: 8.0.0.783 (R2012b)
MATLAB License Number: ******
Operating System: Microsoft Windows 7 Version 6.1 (Build 7601: Service Pack 1)
Java Version: Java 1.6.0_17-b04 with Sun Microsystems Inc. Java HotSpot(TM) Client VM mixed mode
------------------------------------------------------------------------------------------------

[Babak]

if you have an older version of MATLAB, you can do this:

 >> syss = ss(sys)
 >> bandwidth(syss)

[Arthur]

It worked here too.

Version 7.12.0.635(R2011a) 64-bit (win64)

[Lucy]

I have MATLAB Version: 7.14.0.739 (R2012a) on my school campus computers, neither:

bandwidth(sys) (where sys is a tf) or syss=ss(sys)

will work...

Is there something I'm missing or is this an outdated version problem?