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    %% Design Lowpass Filter
% Construct a lowpass object with order, passband-edge frequency,
% stopband-edge frequency, and passband ripple specifications, and then 
% design an elliptic filter.

d = fdesign.lowpass('n,fp,fst,ap',6,20,25,.8,80);
design(d,'ellip'); % Starts FVtool to display the filter.

%%
% Construct a lowpass object with filter order, passband edge frequency, 
% passband ripple, and stopband attenuation specifications, and then 
% design an elliptic filter.
d = fdesign.lowpass('n,fp,ap,ast',6,20,.8,60,80);
design(d,'ellip'); % Starts FVTool to display the filter.