tf command not working correctly

Hello,
I am not sure why this is happening. I ran this command in MATLAB
sys=tf([4],[1 2 0])
and got this as the answer.
sys =
s^20 + 1.5 s^19 + 2 s^18 + 2.5 s^17 + 3 s^16 + 3.5 s^15
+ 4 s^14 + 4.5 s^13 + 5 s^12 + 5.5 s^11 + 6 s^10
+ 5.5 s^9 + 5 s^8 + 4.5 s^7 + 4 s^6 + 3.5 s^5
+ 3 s^4 + 2.5 s^3 + 2 s^2 + 1.5 s + 1
--------------------------------------------------------------
s^20 + 1.5 s^19 + 2 s^18 + 2.5 s^17 + 3 s^16 + 3.5 s^15
+ 4 s^14 + 4.5 s^13 + 5 s^12 + 5.5 s^11 + 6 s^10
+ 5.5 s^9 + 5 s^8 + 4.5 s^7 + 4 s^6 + 3.5 s^5
+ 3 s^4 + 2.5 s^3 + 2 s^2 + 1.5 s + 1
This is not the correct answer to the transfer function.
Do you know what I can do to fix this?
Thank you

4 comentarios

Adam Danz
Adam Danz el 31 de Mzo. de 2020
I get the expected output. Are you sure your code doesn't have a typo in the inputs?
sys=tf([4],[1 2 0])
sys =
4
---------
s^2 + 2 s
Continuous-time transfer function.
% list tf() fuctions & methods on path
>> which tf -all
C:\Program Files\MATLAB\R2019b\toolbox\control\ctrlmodels\@tf\tf.m % tf constructor
C:\Program Files\MATLAB\R2019b\toolbox\control\ctrlmodels\@DynamicSystem\tf.m % DynamicSystem method
C:\Program Files\MATLAB\R2019b\toolbox\shared\controllib\engine\+ltipack\@tfdata\tf.m % ltipack.tfdata method
C:\Program Files\MATLAB\R2019b\toolbox\ident\ident\@idParametric\tf.m % idParametric method
C:\Program Files\MATLAB\R2019b\toolbox\mpc\mpc\@mpc\tf.m % mpc method
C:\Program Files\MATLAB\R2019b\toolbox\shared\controllib\engine\@StaticModel\tf.m % StaticModel method
Grace Normoyle
Grace Normoyle el 31 de Mzo. de 2020
So, I am just trying to run that line there are no other code or inputs.
When I open the MATLAB I get these errors.
Unable to perform assignment because the left and right sides have a different number of elements.
Error in matlab.internal.builtinhelper.repmat (line 53)
siz(idx) = double(full(checkSizesType(arg)));
Error in matlab.supportpackagemanagement.internal.getInstalledSupportPackagesInfo (line 15)
installedSupportPackages = repmat( ...
Unable to perform assignment because the left and right sides have a different number of elements.
Error in matlab.internal.builtinhelper.repmat (line 53)
siz(idx) = double(full(checkSizesType(arg)));
Error in matlab.internal.addons.updates.getSupportPackageUpdates (line 23)
supportPackageUpdates = repmat( ...
Adam Danz
Adam Danz el 1 de Abr. de 2020
See this thread. There are two different answers. Try the accepted answer first. If that doesn't work, try the 2nd answer. If neither work, contact MathWorks support.

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