Re: Gaussian fit of a peak

[Ben Abbott]

On Sep 17, 2008, at 4:58 PM, Andrea Cimatoribus wrote:

> In matlab, I used function "fit". Data are intensity as a function of
> energy. Of course, you can think it as an histogram of event number as
> a function of energy.
> Andrea
>
> 2008/9/17 Ben Abbott <address@hidden>:
> > On Wednesday, September 17, 2008, at 10:20AM, "Andrea Cimatoribus" <address@hidden 
> > > wrote:
> > > Hi everybody,
> > > I am an absolute novice of octave, even though I have some  
> > > experience
> > > with matlab.
> > > Just to get the feeling of octave, I am presently translating a  
> > > simple
> > > (but very useful to me) script, that basically sums data with a peak
> > > structure. In order to do this properly, I need to centre each new
> > > spectrum on the zero, that is the peak maximum. My strategy, in
> > > matlab, was to make a preliminary gaussian fit, whose result was  
> > > to be
> > > confirmed through a graphical input, to get the "zero" of the
> > > spectrum. As of now, I am trying to understand how can I make a
> > > gaussian fit of the data in octave. Data is simply organised as a
> > > matrix [x,y]. Is there a built function? Sorry but I can't find
> > > anything with online help.
> > > Andrea
> >
> > How did you do it in Matlab?
> >
> > If the data is statistical, then I'd recommend you calculate the  
> > median and standard deviation and construct the gaussian  
> > distribution from that.
> >
> > By "sums data with a peak structure" do you mean you are  
> > constructing a histogram?

"fit" is part of the curefit toolbox, correct?

In any event, there is a package available from MathWorks File  
Exchange called "fit" I thought would work, but Octave's fminsearch  
has some trouble with it. If you'd like to track down the specifics ...

        
http://www.mathworks.com/matlabcentral/fileexchange/loadFile.do?objectId=8468

You'll need Octave's optimization package

        http://octave.sourceforge.net/doc/optimization.html

Ben