# how to do bi-lateral Z-transform in Matlab?

Started by May 18, 2005
```Hi all,

I wanted to use bi-lateral Z-transform, and esp. I wanted to use Inverse
Bilateral Z-transform...

But Matlab only provides Uni-lateral Z-transform and Inverse Transofrm
through its "ztrans" and "iztrans" command pair...

How to do Bi-lateral Z-transfrom using Matlab?

Thanks a lot!

```
```Hi Kiki,
->    you can compute the poles using the Residue comman in MATLAB.
-> Then compute the absolutely values of poles to find out which ones
lie within or outside unit circle.
-> inverse transform for each of these can be determined by the
unilateral transform function separately (atleast for ones within unit
circle).

-> For ones outside the unit circle, we use the known z-transform of a
left-handed exponential

->Also poles outside unit circle only contribute to the causal part at
time zero...

Piyush

kiki wrote:
> Hi all,
>
> I wanted to use bi-lateral Z-transform, and esp. I wanted to use
Inverse
> Bilateral Z-transform...
>
> But Matlab only provides Uni-lateral Z-transform and Inverse
Transofrm
> through its "ztrans" and "iztrans" command pair...
>
> How to do Bi-lateral Z-transfrom using Matlab?
>
> Thanks a lot!

```