User`s guide

Table Of Contents

Creating LTI Models

2-23

produces the transfer function

which differs from by a factor .

To avoid such convention clashes, the Control System Toolbox offers a separate

function

filt dedicated to the DSP-like specification of transfer functions. Its

syntax is

h = filt(num,den)

for discrete tra nsfer functions with unspecified sample time, and

h = filt(num,den,Ts)

to further specify the sample time Ts. This function creates TF objects just like

tf,butexpectsnum and den to list the numerator and denominator coefficients

in ascending powers of . F or example, typing

h = filt([1 0.5],[1 2 3])

produces

Transfer function:

1 + 0.5 z^–1

-------------------

1 + 2 z^–1 + 3 z^–2

Sampling time: unspecified

You can also use filt to specify MIMO transferfunctions in . Just as for tf,

the input arguments

num and den are t hen cell arrays of row vectors of

appropriate dimensions (see “Transfer Function Models” on page 2-8 for

details). Note that each row vector should comply with the “ascending powers

of ” convention.

z 0.5

2z 3++

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()

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