www.pudn.com > 666bandelets_toolbox.zip > keep_biggest.m

function y = keep_biggest(x,n) 
 
% keep_biggest - keep only the n biggest coef,  
%   set the rest to zero. 
% 
% y = keep_biggest(x,n); 
% 
%   Copyright (c) 2004 Gabriel Peyré 
 
if iscell(x) 
    % concat cells array 
    xx = []; 
    for i=1:length(x) 
        xx = [xx;x{i}(:)]; 
    end 
    yy = keep_biggest(xx,n); 
    % recreate cells 
    for i=1:length(x) 
        y{i} = yy( 1:prod( size(x{i}) ) ); 
        y{i} = reshape(y{i}, size(x{i})); 
        yy( 1:prod( size(x{i}) ) ) = []; 
    end 
    return; 
end 
 
n = round(n); 
y = x; 
[tmp,I] = sort(abs(y(:))); 
y( I(1:end-n) ) = 0;