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extr.m完整源程序
在网上找到了如下:
extr函数的链接: http://perso.ens-lyon.fr/patrick.flandrin/EDSFA_mfiles/extr.m
function [indmin, indmax, indzer] = extr(x,t);
% [indmin, indmax, indzer] = EXTR(x,t) finds extrema and zero-crossings
%
% inputs : - x : analyzed signal
% - t (optional) : sampling times, default 1:length(x)
%
% outputs : - indmin = indices of minima
% - indmax = indices of maxima
% - indzer = indices of zero-crossings
if(nargin==1), t=1:length(x); end
m = length(x); x1=x(1:m-1); x2=x(2:m); indzer = find(x1.*x2<0);
if any(x == 0)
iz = find( x==0 ); indz = [];
if any(diff(iz)==1)
zer = x == 0; dz = diff([0 zer 0]);
debz = find(dz == 1); finz = find(dz == -1)-1;
indz = round((debz+finz)/2);
else
indz = iz;
end
indzer = sort([indzer indz]);
end
d = diff(x);
n = length(d); d1 = d(1:n-1); d2 = d(2:n);
indmin = find(d1.*d2<0 & d1<0)+1;
indmax = find(d1.*d2<0 & d1>0)+1;
if any(d==0)
imax = []; imin = [];
bad = (d==0); dd = diff([0 bad 0]);
debs = find(dd == 1); fins = find(dd == -1);
if debs(1) == 1
if length(debs) > 1
debs = debs(2:end); fins = fins(2:end);
else
debs = []; fins = [];
end
end
if length(debs) > 0
if fins(end) == m
if length(debs) > 1
debs = debs(1:(end-1)); fins = fins(1:(end-1));
else
debs = []; fins = [];
end
end
end
lc = length(debs);
if lc > 0
for k = 1:lc
if d(debs(k)-1) > 0
if d(fins(k)) < 0
imax = [imax round((fins(k)+debs(k))/2)];
end
else
if d(fins(k)) > 0
imin = [imin round((fins(k)+debs(k))/2)];
end
end
end
end
if length(imax) > 0, indmax = sort([indmax imax]); end
if length(imin) > 0, indmin = sort([indmin imin]); end
end
[ 本帖最后由 ChaChing 于 2009-12-9 18:33 编辑 ] |
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