Convert model from continuous to discrete time

discretizes the continuous-time dynamic system
model
`sysd`

= c2d(`sysc`

,`Ts`

)`sysc`

using zero-order hold on the inputs and a sample time of
`Ts`

.

Convert Model Rate | `c2dOptions`

| `d2c`

| `d2d`

| `thiran`

| `translatecov`