delay2z (Control System Toolbox)

Replace delays of discrete-time TF, SS, or ZPK models by poles at z=0, or replace delays of FRD models by a phase shift

Syntax

```
sys = delay2z(sys) 
```

Description

sys = delay2z(sys) maps all time delays to poles at z=0 for discrete-time TF, ZPK, or SS models sys. Specifically, a delay of k sampling periods is replaced by (1/z)^k in the transfer function corresponding to the model.

For FRD models, delay2z absorbs all time delays into the frequency response data, and is applicable to both continuous- and discrete-time FRDs.

Example

z=tf('z',-1);
sys=(-.4*z -.1)/(z^2 + 1.05*z + .08)
Transfer function:
-0.4 z - 0.1
-------------------
z^2 + 1.05 z + 0.08
Sampling time: unspecified
sys.InputDelay = 1;
sys = delay2z(sys)
Transfer function:
     -0.4 z - 0.1
-----------------------
z^3 + 1.05 z^2 + 0.08 z
Sampling time: unspecified

See Also
hasdelay True for LTI models with delays

pade Pade approximation of time delays

totaldelay Combine delays for an LTI model

dcgain dlqr