%% Design an Equiripple FIR Filter with a Direct-Form Transposed Structure
% This example designs an equiripple filter with a direct-form transposed structure by specifying the 'FilterStructure' argument. To set the design options for the filter, use the designopts method and options object  opts.

d = fdesign.lowpass('fp,fst,ap,ast');
opts = designopts(d,'equiripple');
opts.FilterStructure='dffirt';
opts.DensityFactor=20

%

firFilt = design(d,'equiripple','SystemObject',true,opts)

%

fvtool(firFilt);

% The MaxPhase design option for equripple FIR filters is currently only available for lowpass, highpass, bandpass, and bandstop filters.
% Copyright 2012 The MathWorks, Inc.