User`s guide

Filter Realization Wizard
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Numerator field. The two filter sections do not need to have the same
order.
- Type
{a1,a2} in the Denominator text field. Note that the denominator
coefficient vector for each section is also entered as an element in a cell
array. Since this is a two-section filter, a two-cell array is specified in the
Denominator field.
3 Type a name for the new filter subsystem in the Block Name field. The
example uses
Butter Sections.
4 Press the Build button to create the specified filter subsystem in a new
model window.
5 Double-click the new Butter Sections block to see the Direct-Form II filter
realization that the Wizard created.
Example 4: ARMA Lattice
Design a fourth-order, quarter-band, lowpass Butterworth filter using an
ARMA lattice:
1 At the MATLAB command line, compute the lattice and ladder coefficients
(
k and v, respectively) for the ARMA filter.
[b,a] = butter(4,.25);