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Re: test this in matlab for my please

 From: Doug Stewart Subject: Re: test this in matlab for my please Date: Tue, 15 Mar 2016 12:07:16 -0400

On Tue, Mar 15, 2016 at 10:34 AM, Nicholas Jankowski wrote:
On Tue, Mar 15, 2016 at 9:52 AM, Doug Stewart wrote:

On Fri, Mar 11, 2016 at 1:17 PM, Doug Stewart wrote:

On Fri, Mar 11, 2016 at 1:00 PM, Nicholas Jankowski wrote:
On Fri, Mar 11, 2016 at 12:41 PM, Doug Stewart wrote:

2016-03-11 12:28 GMT-05:00 Doug Stewart :
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

--
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
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))

--
DAS

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