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%% Daubechies' Extremal Phase Scaling Filter with Specified Sum % This example shows to determine the Daubechies' extremal phase scaling % filter with a specified sum. The two most common values for the sum are % $\sqrt{2}$ and 1. %% % Construct two versions of the |'db4'| scaling filter. One scaling filter % sums to $\sqrt{2}$ and the other version sums to 1. % Copyright 2015 The MathWorks, Inc. NumVanishingMoments = 4; h = dbaux(NumVanishingMoments,sqrt(2)); m0 = dbaux(NumVanishingMoments,1); %% % The filter with sum equal to $\sqrt{2}$ is the synthesis (reconstruction) % filter returned by |wfilters| and used in the discrete wavelet transform. [LoD,HiD,LoR,HiR] = wfilters('db4'); max(abs(LoR-h)) %% % For orthogonal wavelets, the analysis (decomposition) filter is the % time-reverse of the synthesis filter. max(abs(LoD-fliplr(h)))