%calculate each imf's autocorrelation coefficient,from which
%we can decide the num of imfs that currupted by heavy noise.
%that means we can utilize the autocorrelation coefficient to decide the
%noise order
function signal=emd5(x)
tic;%timing function.
if size(x,2)==1
    x=x';
end
n=x;%give the value of n to x.
emd(n);%invoke the emd function to devite the signal into imfs.
a=ans;
imfnum=size(a,1)
i1=1;
while i1<=imfnum
    r=a(i1,:);
    %Treat adjacent imfs with autocorrelation function.
    n=20;
    i=length(r);
    b=[];
    for j=1:(i-n)
        b(j)=r(j+n);
    end
    i=length(b);
    m=1:i;
    for j=1:n
        b(i+j)=interp1(m,b,i+j,'spline');%utilize the cubic spline function to make up of the length of b to accord r.
        m=1:i+j;
    end
    P=corrcoef(b,r);
    P=abs(P(2,1));
    if P>0.2
        break;
    else
        i1=i1+1;
        continue;
    end
end
i1=min(i1,5)
signal=add(a,i1,imfnum);
autocorrelation(signal);
toc;
return;