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),'-.');