coronajs.m

老外写的小波变换的工具箱

function [xhat,yh] = CoronaJS(y,L)
% CoronaJS -- James-Stein applied to ``Littlewood-Paley'' Fourier Coronae
% Usage
%   [xhat,xhathat] = CoronaJS(y,L)
% Inputs
%   y      array of dyadic length 2^J
%          NORMALIZED TO NOISE LEVEL 1 (See NOISENORM)
%   L      Low-Frequency cutoff for shrinkage (e.g. L=4)
%          SHOULD BE L << J
% Outputs
%   xhat   estimate, obtained by James-Stein Shrinkage
%          on Dyadic Coronae
%   xhhat  Fourier Transform of estimate
%
	[n,J] = dyadlength(y);
	yh = fft(y); i=sqrt(-1);
	for j=L:(J-1) ,
	   lo = 2^(j-1)+1; hi = 2^j;
	   sel = lo:hi;
	   v = [real(yh(sel)) imag(yh(sel))];
	   vsh = JamesStein(v./sqrt(n/2)).*sqrt(n/2);
	   k = 2^(j-1);
	   yh(sel) = vsh(1:k) + i*vsh((k+1):(2*k));
	end
	yh((n/2)+1) = 0;
	yh(((n/2)+2):n) = conj(yh((n/2):-1:2));
	xhat = real(ifft(yh));
    
 
 
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%  Part of Wavelab Version 850
%  Built Tue Jan  3 13:20:41 EST 2006
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