peakdet

 PEAKDET Detect peaks in a vector
 
 [MAXTAB, MINTAB] = PEAKDET(V, DELTA) finds the local
 maxima and minima ("peaks") in the vector V.
 MAXTAB and MINTAB consists of two columns. Column 1
 contains indices in V, and column 2 the found values.
 
 With [MAXTAB, MINTAB] = PEAKDET(V, DELTA, X) the indices
 in MAXTAB and MINTAB are replaced with the corresponding
 X-values.
 
 A point is considered a maximum peak if it has the maximal
 value, and was preceded (to the left) by a value lower by
 DELTA.
 
 Eli Billauer, 3.4.05 (Explicitly not copyrighted).
 This function is released to the public domain; Any use is allowed.
 
 Modified by Abdallah Kassir 13/12/2009

0001 function maxtab=peakdet(v)
0002 % PEAKDET Detect peaks in a vector
0003 %
0004 % [MAXTAB, MINTAB] = PEAKDET(V, DELTA) finds the local
0005 % maxima and minima ("peaks") in the vector V.
0006 % MAXTAB and MINTAB consists of two columns. Column 1
0007 % contains indices in V, and column 2 the found values.
0008 %
0009 % With [MAXTAB, MINTAB] = PEAKDET(V, DELTA, X) the indices
0010 % in MAXTAB and MINTAB are replaced with the corresponding
0011 % X-values.
0012 %
0013 % A point is considered a maximum peak if it has the maximal
0014 % value, and was preceded (to the left) by a value lower by
0015 % DELTA.
0016 %
0017 % Eli Billauer, 3.4.05 (Explicitly not copyrighted).
0018 % This function is released to the public domain; Any use is allowed.
0019 %
0020 % Modified by Abdallah Kassir 13/12/2009
0021 
0022 
0023 x=1:length(v);
0024 [v,x]=cadj(v,x);
0025 delta=(max(v)-min(v))/4;
0026 
0027 maxtab = [];
0028 
0029 if delta==0
0030     return;
0031 end
0032 
0033 mn = Inf; mx = -Inf;
0034 mxpos = NaN;
0035 
0036 lookformax = 0;  %modified
0037 
0038 for i=1:length(v)
0039   this = v(i);
0040   if this > mx, mx = this; mxpos = x(i); end
0041   if this < mn, mn = this; end
0042   
0043   if lookformax
0044     if this < mx-delta
0045       maxtab = [maxtab ; mxpos mx];
0046       mn = this;
0047       lookformax = 0;
0048     end  
0049   else
0050     if this > mn+delta
0051       mx = this; mxpos = x(i);
0052       lookformax = 1;
0053     end
0054   end
0055 end