www.pudn.com > duoxiangshinihe.rar > duoxiangshinihe.m, change:2009-04-22,size:3960b

```t=linspace(1,100,100);
s=cos(2*pi*t/50)+0.6*cos(2*pi*t/25)+0.5*sin(2*pi*t/200);
plot(t(5:95),s(5:95));%(需要延拓的信号)
[indmin,indmax,indzer] = extr(s);%(找出近端点极值点，两端极小15，85)
envmax = interp1( [t(5) t(indmax) t(95)],[s(5) s(indmax) s(95)],t(5:95),'spline');
envmin = interp1( [t(5) t(indmin) t(95)],[-0.7304 s(indmin) -0.6947],t(5:95),'spline');
envmoy=(envmax+envmin)/2;
plot(t(5:95),s(5:95),'-',t(5:95),envmax,'*',t(5:95),envmin,'+',t(5:95),envmoy,'.');

t=linspace(1,100,100);
NBSYM=2;
xx=cos(2*pi*t/50)+0.6*cos(2*pi*t/25)+0.5*sin(2*pi*t/200);
lx=length(xx);
[indmin,indmax,indzer] = extr(xx);
lm=length(indmin);
lM=length(indmax);
nem=lm + lM;
nzm=length(indzer);

% boundary conditions for interpolations :

if indmax(1) < indmin(1)
if xx(1) > xx(indmin(1))
lmax = fliplr(indmax(2:min(size(indmax,2),NBSYM+1)));
lmin = fliplr(indmin(1:min(size(indmin,2),NBSYM)));
lsym = indmax(1);
else
lmax = fliplr(indmax(1:min(size(indmax,2),NBSYM)));
lmin = [fliplr(indmin(1:min(size(indmin,2),NBSYM-1))),1];
lsym = 1;
end
else

if xx(1) < xx(indmax(1))
lmax = fliplr(indmax(1:min(size(indmax,2),NBSYM)));
lmin = fliplr(indmin(2:min(size(indmin,2),NBSYM+1)));
lsym = indmin(1);
else
lmax = [fliplr(indmax(1:min(size(indmax,2),NBSYM-1))),1];
lmin = fliplr(indmin(1:min(size(indmin,2),NBSYM)));
lsym = 1;
end
end

if indmax(end) < indmin(end)
if xx(end) < xx(indmax(end))
rmax = fliplr(indmax(max(size(indmax,2)-NBSYM+1,1):size(indmax,2)));
rmin = fliplr(indmin(max(size(indmin,2)-NBSYM,1):(size(indmin,2)-1)));
rsym = indmin(end);
else
rmax = [lx,fliplr(indmax(max(size(indmax,2)-NBSYM+2,1):size(indmax,2)))];
rmin = fliplr(indmin(max(size(indmin,2)-NBSYM+1,1):size(indmin,2)));
rsym = lx;
end
else
if xx(end) > xx(indmin(end))
rmax = fliplr(indmax(max(size(indmax,2)-NBSYM,1):(size(indmax,2)-1)));
rmin = fliplr(indmin(max(size(indmin,2)-NBSYM+1,1):size(indmin,2)));
rsym = indmax(end);
else
rmax = fliplr(indmax(max(end-NBSYM+1,1):size(indmax,2)));
rmin = [lx,fliplr(indmin(max(size(indmin,2)-NBSYM+2,1):size(indmin,2)))];
rsym = lx;
end
end

tlmin = 2*t(lsym)-t(lmin);
tlmax = 2*t(lsym)-t(lmax);
trmin = 2*t(rsym)-t(rmin);
trmax = 2*t(rsym)-t(rmax);

% in case symmetrized parts do not extend enough
if tlmin(1) > t(1) | tlmax(1) > t(1)
if lsym == indmax(1)
lmax = fliplr(indmax(1:min(size(indmax,2),NBSYM)));
else
lmin = fliplr(indmin(1:min(size(indmin,2),NBSYM)));
end
if lsym == 1
error('bug')
end
lsym = 1;
tlmin = 2*t(lsym)-t(lmin);
tlmax = 2*t(lsym)-t(lmax);
end

if trmin(end) < t(lx) | trmax(end) < t(lx)
if rsym == indmax(end)
rmax = fliplr(indmax(max(size(indmax,2)-NBSYM+1,1):size(indmax,2)));
else
rmin = fliplr(indmin(max(size(indmin,2)-NBSYM+1,1):size(indmin,2)));
end
if rsym == lx
error('bug')
end
rsym = lx;
trmin = 2*t(rsym)-t(rmin);
trmax = 2*t(rsym)-t(rmax);
end

xxlmax =xx(lmax);
xxlmin =xx(lmin);
xxrmax =xx(rmax);
xxrmin =xx(rmin);

% definition of envelopes from interpolation

envmax1 = interp1([tlmax t(indmax) trmax],[xxlmax xx(indmax) xxrmax],t,'spline');
envmin1 = interp1([tlmin t(indmin) trmin],[xxlmin xx(indmin) xxrmin],t,'spline');
envmoy1=(envmax1+envmin1)/2;

plot(t(5:95),s(5:95),'-',t(5:95),envmax,'*',t(5:95),envmin,'+',t(5:95),envmoy,'.' ,t(5:95),envmax1(5:95),'+',t(5:95),envmin1(5:95),'*',t(5:95),envmoy1(5:95),'-.');```