Specifications

d2c
16-49
16d2c
Purpose Convert discrete-time LTI models to continuous time
Syntax sysc = d2c(sysd)
sysc = d2c(sysd,method)
Description d2c converts LTI models from discrete to continuous time using one of the
following conversion methods:
The string
method specifies the conversion method. If method is omitted then
zero-order hold (
'zoh') is assumed. See “Continuous/Discrete Conversions of
LTI Models” in Chapter 3 of this manual and reference [1] for more details on
the conversion methods.
Example Consider the discrete-time model with transfer function
and sample time second. You can derive a continuous-time
zero-order-hold equivalent model by typing
Hc = d2c(H)
DiscretizingtheresultingmodelHc with the zero-order hold method (this is the
default method) and sampling period gives back the original discrete
model . To see this, type
c2d(Hc,0.1)
To use the Tustin approximation instead of zero-order hold, type
Hc = d2c(H,'tustin')
As with zero-order hold, the inverse discretization operation
'zoh'
Zero-order hold on the inputs. The control inputs are
assumed piecewise constant over the sampling period.
'tustin'
Bilinear (Tustin) approximation to the derivative.
'prewarp'
Tustin approximation with frequency prewarping.
'matched'
Matched pole-zero method of [1] (for SISO systems only).
Hz
()
z 1–
z
2
z 0.3++
-----------------------------
=
T
s
0.1=
T
s
0.1=
Hz
()