opts = c2dOptions returns
the default options for c2d.

opts = c2dOptions('OptionName', OptionValue) accepts
one or more comma-separated name/value
pairs that specify options for the c2d command. Specify OptionName inside
single quotes.

Input Arguments

Name-Value Pair Arguments

'Method'

Discretization method, specified as one of the following values:

'zoh'

Zero-order hold, where c2d assumes
the control inputs are piecewise constant over the sampling period Ts.

'foh'

Triangle
approximation (modified first-order hold), where c2d assumes
the control inputs are piecewise linear over the sampling period Ts.
(See [1], p. 228.)

'impulse'

Impulse-invariant discretization.

'tustin'

Bilinear (Tustin) approximation.
By default, c2d discretizes with no prewarp and
rounds any fractional time delays to the nearest multiple of the sample
time. To include prewarp, use the PrewarpFrequency option.
To approximate fractional time delays, use theFractDelayApproxOrder option.

'matched'

Zero-pole
matching method. (See [1], p. 224.) By default, c2d rounds
any fractional time delays to the nearest multiple of the sample time.
To approximate fractional time delays, use the FractDelayApproxOrder option.

Default: 'zoh'

'PrewarpFrequency'

Prewarp frequency for 'tustin' method, specified
in rad/TimeUnit, where TimeUnit is
the time units, specified in the TimeUnit property,
of the discretized system. Takes positive scalar values. A value of
0 corresponds to the standard 'tustin' method without
prewarp.

Default: 0

'FractDelayApproxOrder'

Maximum order of the Thiran filter used to approximate fractional
delays in the 'tustin' and 'matched' methods.
Takes integer values. A value of 0 means that c2d rounds
fractional delays to the nearest integer multiple of the sample time.

Default: 0

Examples

Discretize two models using identical discretization options.

Then,
discretize both models using the option set.

dsys1 = c2d(sys1, 0.1, opt); % 0.1s sampling time
dsys2 = c2d(sys2, 0.2, opt); % 0.2s sampling time

The c2dOptions option set does not include the sampling time Ts.
You can use the same discretization options to discretize systems
using a different sampling time.

References

[1] Franklin, G.F., Powell, D.J., and Workman,
M.L., Digital Control of Dynamic Systems (3rd
Edition), Prentice Hall, 1997.