%% Valid Filter Structures
% Design a default lowpass filter specification object. Return all valid design methods and structures in a structure array. Display the fieldnames to see all valid design methods. Display the valid filter structures for the equiripple field.

D = fdesign.lowpass;
filtstruct = validstructures(D);

fn = fieldnames(filtstruct)
strs = eval(['filtstruct.' fn{5}])

%
% Create a highpass filter of order 50 with a 3-dB frequency of 0.2. Obtain the available structures for a Butterworth design.

D = fdesign.highpass('N,F3dB',50,0.2);
C = validstructures(D,'butter')

% Copyright 2012 The MathWorks, Inc.