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## Auto Peak Finder & Analyser

version 1.0 (3.17 KB) by

Finds peaks, locations, fwhms and area in signal.

Updated

Very lean an simple code that automatically finds major peaks, their locations, fwhms and area in a given signal y versus x. Requires no input parameters. The output is a matrix with peaks sorted in rows and following columns:

output = peak No. | peak Y | peak X | peak fwhm | peak area

leo

### leo (view profile)

Thanks. It has been very helpful

John

### John (view profile)

I got an error in line 82
"Subscript indices must either be real positive integers or logicals".
because in some case ipeak-indfwhms equals a negative number

Eric Diaz

### Eric Diaz (view profile)

The above error is a flaw in the code. The programmer forgot to include a check for what happens during shifting of signal when the peak index is too small or too large (i.e., at the edges of the matrix).

One could include the following code just before the shifting to bypass all peaks near the edges. Just define number of elements to ignore on each edge.

% check if index too big
if ipeak >= length(y)-numElements
break
end

% check if index too small
if ipeak <= numElements
break
end

sam s

### sam s (view profile)

hi,
when i launch this programm i have an error :

Subscript indices must either be real positive integers or logicals.

Error in ==> autopeak at 75
y_shift2(ifwhms(1)-1:ifwhms(1)+1) = y_shift2(ifwhms(1)-1:ifwhms(1)+1) + peak(i);

Donald

### Donald (view profile)

yy = smooth(y) smooths the data in the column vector y using a moving average filter. Results are returned in the column vector yy. The default span for the moving average is 5.

The first few elements of yy are given by

yy(1) = y(1)
yy(2) = (y(1) + y(2) + y(3))/3
yy(3) = (y(1) + y(2) + y(3) + y(4) + y(5))/5
yy(4) = (y(2) + y(3) + y(4) + y(5) + y(6))/5

So if you do not have the MATLAB "Curve Fitting Toolbox", you can make your own smooth function from the above description.

Claus Jeppesen

### Claus Jeppesen (view profile)

Theo...what version are you using?? Smooth.m is not a standard file in my matlab version. Maybe you could upload it

Theo

### Theo (view profile)

smooth works fine, it's a standard function in my matlab. maybe you don't have the right addons

Martin Barlett

### Martin Barlett (view profile)

Ditto -- need to add your smooth function or remove this posting!

Rose Cory

### Rose Cory (view profile)

Am I missing a smooth.m file to run this code?

##### MATLAB Release
MATLAB 7.5 (R2007b)