Re: test this in matlab for my please

[Nicholas Jankowski]

On Tue, Mar 15, 2016 at 12:07 PM, Doug Stewart <address@hidden> wrote:

On Tue, Mar 15, 2016 at 10:34 AM, Nicholas Jankowski <address@hidden> wrote:

On Tue, Mar 15, 2016 at 9:52 AM, Doug Stewart <address@hidden> wrote:

On Fri, Mar 11, 2016 at 1:17 PM, Doug Stewart <address@hidden> wrote:

On Fri, Mar 11, 2016 at 1:00 PM, Nicholas Jankowski <address@hidden> wrote:

On Fri, Mar 11, 2016 at 12:41 PM, Doug Stewart <address@hidden> wrote:

2016-03-11 12:28 GMT-05:00 Doug Stewart <address@hidden>:

Would someone kindly run this in matlab and post the results for me.

Thanks

s=tf('s')

sys=1/s

c2d(sys,.1,'zoh')

c2d(sys,.1,'matched')

c2d(sys,.1,'tustin')

sys=1/(s^2)

c2d(sys,.1,'zoh')

c2d(sys,.1,'matched')

c2d(sys,.1,'tustin')

sys=1/(s*(s+1))

c2d(sys,.1,'zoh')

c2d(sys,.1,'matched')

c2d(sys,.1,'tustin')

--

DAS

try again please

--

DAS

no errors this time:

>>
s=tf('s')
sys=1/s
c2d(sys,.1,'zoh')
c2d(sys,.1,'matched')
c2d(sys,.1,'tustin')

sys=1/(s^2)
c2d(sys,.1,'zoh')
c2d(sys,.1,'matched')
c2d(sys,.1,'tustin')

sys=1/(s*(s+1))
c2d(sys,.1,'zoh')
c2d(sys,.1,'matched')
c2d(sys,.1,'tustin')

s =
 
  s
 
Continuous-time transfer function.


sys =
 
  1
  -
  s
 
Continuous-time transfer function.


ans =
 
   0.1
  -----
  z - 1
 
Sample time: 0.1 seconds
Discrete-time transfer function.


ans =
 
  0.1001
  ------
  z - 1
 
Sample time: 0.1 seconds
Discrete-time transfer function.


ans =
 
  0.05 z + 0.05
  -------------
      z - 1
 
Sample time: 0.1 seconds
Discrete-time transfer function.


sys =
 
   1
  ---
  s^2
 
Continuous-time transfer function.


ans =
 
  0.005 z + 0.005
  ---------------
   z^2 - 2 z + 1
 
Sample time: 0.1 seconds
Discrete-time transfer function.


ans =
 
  0.005003 z + 0.005003
  ---------------------
      z^2 - 2 z + 1
 
Sample time: 0.1 seconds
Discrete-time transfer function.


ans =
 
  0.0025 z^2 + 0.005 z + 0.0025
  -----------------------------
          z^2 - 2 z + 1
 
Sample time: 0.1 seconds
Discrete-time transfer function.


sys =
 
     1
  -------
  s^2 + s
 
Continuous-time transfer function.


ans =
 
  0.004837 z + 0.004679
  ----------------------
  z^2 - 1.905 z + 0.9048
 
Sample time: 0.1 seconds
Discrete-time transfer function.


ans =
 
  0.004761 z + 0.004761
  ----------------------
  z^2 - 1.905 z + 0.9048
 
Sample time: 0.1 seconds
Discrete-time transfer function.


ans =
 
  0.002381 z^2 + 0.004762 z + 0.002381
  ------------------------------------
         z^2 - 1.905 z + 0.9048
 
Sample time: 0.1 seconds
Discrete-time transfer function.

Thanks again.

From this I see that the "matched" results are different than octaves

by about 5%

Doug

--

DAS

Would you please run this on Matlab for me ,and post the results.

I am still trying to track down an error in control pkg.

s=tf('s')

sys=1/s

c2d(sys,.1,'matched')

c2d(sys,.1,'impulse')

[a, b, c, d, e, stname] =ssdata(sys)

sys=1/(s^2)

c2d(sys,.1,'matched')

c2d(sys,.1,'impulse')

[a, b, c, d, e, stname] =ssdata(sys)

sys=1/(s*(s+1))

c2d(sys,.1,'matched')

c2d(sys,.1,'impulse')

[a, b, c, d, e, stname] =ssdata(sys)

s =
 
  s
 
Continuous-time transfer function.


sys =
 
  1
  -
  s
 
Continuous-time transfer function.


ans =
 
  0.1001
  ------
  z - 1
 
Sample time: 0.1 seconds
Discrete-time transfer function.


ans =
 

  0.1 z
  -----
  z - 1
 
Sample time: 0.1 seconds
Discrete-time transfer function.

Warning: Obsolete syntax. Use the "InputDelay" property to access input delays in LTI models.
> In ctrlMsgUtils.warning (line 25)
  In DynamicSystem/ssdata (line 103)

a =

     0


b =

     1


c =

     1


d =

     0


e =

     0


stname =

     0


sys =
 
   1
  ---
  s^2
 
Continuous-time transfer function.


ans =
 
  0.005003 z + 0.005003
  ---------------------
      z^2 - 2 z + 1
 
Sample time: 0.1 seconds
Discrete-time transfer function.


ans =
 
  0.01 z + 4.441e-18
  ------------------
    z^2 - 2 z + 1
 
Sample time: 0.1 seconds
Discrete-time transfer function.

Warning: Obsolete syntax. Use the "InputDelay" property to access input delays in LTI models.
> In ctrlMsgUtils.warning (line 25)
  In DynamicSystem/ssdata (line 103)

a =

     0     0
     1     0


b =

     1
     0


c =

     0     1


d =

     0


e =

     0


stname =

     0


sys =
 
     1
  -------
  s^2 + s
 
Continuous-time transfer function.


ans =
 
  0.004761 z + 0.004761
  ----------------------
  z^2 - 1.905 z + 0.9048
 
Sample time: 0.1 seconds
Discrete-time transfer function.


ans =
 
        0.009516 z
  ----------------------
  z^2 - 1.905 z + 0.9048
 
Sample time: 0.1 seconds
Discrete-time transfer function.

Warning: Obsolete syntax. Use the "InputDelay" property to access input delays in LTI models.
> In ctrlMsgUtils.warning (line 25)
  In DynamicSystem/ssdata (line 103)

a =

    -1     0
     1     0


b =

     1
     0


c =

     0     1


d =

     0


e =

     0


stname =

     0

One more test  the 2 values printed should be close to 1 but they are

ans =  10.430

ans =  0.31421

in octave.

clear

s=tf('s')

sys=(1/s)

sys=sys*1/(s+1)

[y t x]=impulse(sys,5);

y(length(y))

sys2=ss(sys);

[ y2 t2 x2]=impulse(sys2,5);

y2(length(y2))

s =
 
  s
 
Continuous-time transfer function.


sys =
 
  1
  -
  s
 
Continuous-time transfer function.


sys =
 
     1
  -------
  s^2 + s
 
Continuous-time transfer function.


ans =

    0.9933


ans =

    0.9933