origMode = dwtmode('status','nodisp');
dwtmode('zpd','nodisp')

cfs = 1;
essup = 10; % Essential support of the scaling filter db6. 

for i=1:6 
    % Reconstruct at the top level an approximation 
    % which is equal to zero except at level i where only 
    % one coefficient is equal to 1. 
    rec = upcoef("a",cfs,"db6",i);

    % essup is the essential support of the 
    % reconstructed signal.
    % rec(j) is very small when j is ≥ essup. 
    subplot(6,1,i)
    plot(rec(1:essup))
    xlim([1 325])
    if i<3
        ylim([-1 1])
    elseif i<5
        ylim([-0.5 0.5])
    else
        ylim([-0.2 0.2])
    end
    essup = essup*2; 
end 
subplot(6,1,1) 
title(["Approximation Signals Obtained From a Single " ...
    "Coefficient at Levels 1 to 6"])

cfs = [1]; 
mi = 12; ma = 30;   % Essential support of 
                    % the wavelet filter db6. 
                    
rec = upcoef("d",cfs,"db6",1); 
figure
subplot(6,1,1)
plot(rec(3:12))
axis tight
ylim([-1 1])
for i=2:6 
    % Reconstruct at top level a single detail 
    % coefficient at level i. 
    rec = upcoef("d",cfs,"db6",i);
    subplot(6,1,i)
    plot(rec(mi*2^(i-2):ma*2^(i-2)))
    axis tight
    if i<3
        ylim([-1 1])
    elseif i<5
        ylim([-0.5 0.5])
    else
        ylim([-0.2 0.2])
    end
end 
subplot(6,1,1) 
title(["Detail Signals Obtained From a Single " ... 
    "Coefficient at Levels 1 to 6"])

dwtmode(origMode,'nodisp')