How to extract information from sys

7 views (last 30 days)
David Koenig on 11 May 2019
Commented: Star Strider on 11 May 2019
I would like to extract the coefficients in a discrete transfer function that I construct from a continuous transfer function. For example,
Fs=44100;
Ts=1/Fs;
num=[.001 0 ];
den=[.001 1];
sys=tf(num,den);
sysD=c2d(sys,Ts);
Now, if I do the following:
>> sysD
sysD =
z - 1
----------
z - 0.9776
Sample time: 2.2676e-05 seconds
Discrete-time transfer function.
So,
how can I extract the coefficients a1,a2, b1,b2 in the z-transform
(b1*z+b2)/(a1*z+a2)? That is, can I find b1=1, b2=-1, a1=1, a2=-.9776?
Thanks.

Star Strider on 11 May 2019
The system object is a structure array of cells, so:
N = sysD.Numerator{:}
D = sysD.Denominator{:}
produces:
N =
1 -1
D =
1 -0.977579425259153
That should do what you want.
David Koenig on 11 May 2019
Thanks for you response, Strider. That was exactly what I was looking for!
Star Strider on 11 May 2019
As always, my pleasure!

Categories

Find more on MATLAB in Help Center and File Exchange

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!