c2d (System Identification Toolbox)

Convert a model from continuous time to discrete time.

Syntax

```
md = c2d(mc,T)
md = c2d(mc,T,method)
```

Description

mc is a continuous-time model as any idmodel object (idgrey, idpoly, or idss). md is the model that is obtained when it is sampled with sampling interval T.

Note that the covariance matrix of mc is not translated.

method = 'zoh' (default) makes the translation to discrete time under the assumption that the input is piecewise constant (zero-order hold).

method = 'foh' assumed the input to be piecewise linear between the sampling instants (first-order-hold).

Note that the innovations variance of the continuous-time model is interpreted as the intensity of the spectral density of the noise spectrum. The noise variance in md will thus be given as /T.

idpoly and idss models are returned in the same format. idgrey structures will be preserved if their CDMfile property is equal to `cd'. Otherwise they will be transformed to idss objects.

Examples

Define a continuous-time system and study the poles and zeros of the sampled counterpart.

mc = idpoly(1,1,1,1,[1 1 0],'Ts',0);
md = c2d(mc,0.5);
pzmap(md)

See Also

d2c

cra detrend