[Gambas-user] curve fitting library ?

[Wally]

Randall, Benoit

this example, using the spline stuff from the GSL is one of the most simple 
functions in GSL. All the intersting rest is much more confusing.

Have a look how easy fityk doing a peakfind on very noisy data:
(not sure the mailinglist allow me to attach screenshots )
honmepage: fityk.nieto.pl

On the other hand this fityk is not really free opensource i think.
 
But here is a code example of guessing gaussian peak from a 
clean exp function:
  
#include <iostream>
#include <cmath>

#include <fityk.h>

using namespace std;
using namespace fityk;

int main()
{
    Fityk *f = new Fityk;
    cout << f->get_info("version", true) << endl;
    cout << "ln(2) = " << f->calculate_expr("ln(2)") << endl;
    const double mu = 12.345;
    for (int i = 0; i != 500; ++i) {
        double x = i / 100. + 10;
        double y = ceil(100 * exp(-(x-mu)*(x-mu)/2));
        f->add_point(x, y, sqrt(y));
    }
    f->execute("Y = randnormal(y, s)");
    f->execute("guess %gauss = Gaussian");
    f->execute("fit");
    cout << "peak center: " << f->calculate_expr("%gauss.Center") << endl;
    delete f;
    return 0;
}

output:

Fityk 0.9.8
ln(2) = 0.693147
peak center: 12.3485

So ithink an implematation of GSL (or similar, maybe gnuplot))
would be great - but i'm not able to do it without help. 



On Monday, January 23, 2012 03:06:29 Randall Morgan wrote:
> You must be familiar with C at some level? I'd be surprised if the GSL
> doesn't already have a C wrapper somewhere. I haven't used it in many years
> so I can't recall, and I am sure it has changed. It sounds like you've
> already got a start. So you just need to invest more time into porting GSL
> to Gambas.
> 
> On Mon, Jan 23, 2012 at 2:59 AM, Wally <wally at ...2037...> wrote:
> > On Monday, January 23, 2012 11:47:47 Benoît Minisini wrote:
> > > Le 22/01/2012 09:54, Wally a écrit :
> > > > Does anyone have experience with curve fitting and/or
> > > > peakfinding
> > > > using gambas ?    (e.g. example code)
> > > > 
> > > > Is there a plain C library (Linux) known, suitable to this
> > > > problem
> > > > and gambas ?
> > > > 
> > > > Something like "fityk" (which is written in C++) but written in
> > > > plain C to use with "EXTERN"
> > > > 
> > > > I might wrap the fityk C++ or try Gnu Scientific Library, but
> > > > i'm still searching for alternatives.
> > > > 
> > > > wally
> > > 
> > > There is a GSLSpline example provided with Gambas. Does it help?
> > 
> > I did this example :)
> > 
> > 
> > 
> > 
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