valsurethresh2.m

上課所教所有matlab 小波去燥的教程！~非常適合各位的參考！非常好喔！

function thresh = ValSUREThresh2(y)
%
%%%%%%It's My Own Function!!!
%
% ValSUREThresh -- Adaptive Threshold Selection Using Principle of SURE
%  Usage 
%    thresh = ValSUREThresh(y)
%  Inputs 
%    y        2-d Noisy Data with Std. Deviation = 1
%  Outputs 
%    thresh   Value of Threshold
%
%  Description
%    SURE referes to Stein's Unbiased Risk Estimate.
%
    m=length(y);
    x=[];
    for k=1:m
        x=[x y(k,:)];
    end;
    
	a = sort(abs(x)).^2 ;
	b = cumsum(a);
	n = m*m;%length(x);
	c = linspace(n-1,0,n);
	s = b+c.*a;
	risk = (n - ( 2 .* (1:n ))  + s)/n;
    %figure;plot(1:n,risk(1:n));
	[guess,ibest] = min(risk);
	thresh = sqrt(a(ibest));