How to extract information from sys

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.

Answer 1

[Star Strider]

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]

Thanks for you response, Strider. That was exactly what I was looking for!

[Star Strider]

As always, my pleasure!