enovelope.m

在MATLAB环境下实现二维emd分解的实现

function [y_up,y_low]= Enovelope(x,max,max_No,min,min_No)
%--次端点镜像延拓法获得的上下包络线；
%--注：输入参数是由MaMin函数获得的极值点；
l=length(x);
l1=length(max);
N1=max_No(1)-1;
N2=length(x)-max_No(end);
l2=length(min);
N3=min_No(1)-1;
N4=length(x)-min_No(end);
max1_No(1)=1;
for i=2:(l1+1)
    max1_No(i)=max_No(i-1)+N1; 
end
max1_No(l1+2)=l+N1+N2;
max1(1)=max(1);
for i=2:(l1+1) 
    max1(i)=max(i-1); 
end
max1(l1+2)=max(end);
min1_No(1)=1;
for i=2:(l2+1) 
    min1_No(i)=min_No(i-1)+N3;
end
min1_No(l2+2)=l+N3+N4;
min1(1)=min(1);
for i=2:(l2+1) 
    min1(i)=min(i-1); 
end
min1(l2+2)=min(end);
x1=1:(l+N1+N2);
cs1 = spline(max1_No,max1);
y1=ppval(cs1,x1);
for i=1:l 
    y_up(i)=y1(i+N1);
end
x2=1:(l+N3+N4);
cs2 = spline(min1_No,min1);
y2=ppval(cs2,x2);
for i=1:l 
    y_low(i)=y2(i+N3); 
end