[ROOT] user fit-functions in compiled code

From: Christian Flacco (CJFlacco@lbl.gov)
Date: Thu May 31 2001 - 00:28:13 MEST 

Hello, Rooters,

I am trying to use the user defined fit-function option to fit a TH1F in
stand-alone compiled code.  We are running on Linux, using ROOT version
2.25/03.

I use several ROOT classes in this code, and include the following ROOT
headers:

    #include "TRandom.h"
    #include "TF1.h"
    #include "TH1.h"
    #include "TMath.h"

I declare the TF1 pointer:

    TF1 * scurvef = new TF1("scurve", fitf, -200, 200, 3);

fitf is declared and defined as follows:

    Double_t fitf(Double_t*, Double_t*);

    Double_t fitf(Double_t *x, Double_t *par){
        double arg = 0;
        if (par[2]) arg = (x[0]-par[1])/(1.414*par[2]);
        double fitval = par[0]*0.5*TMath::Erfc(arg);
        return fitval;
    }

I have also tried making the Double_ts into doubles.

The program crashes at the instantiation of TF1 * scurvef, with a
segmentation fault.

Is there something else I need to do to use this method in compiled
code?  (It runs as a ROOT macro.)  An additional include file needed?
Any help would be appreciated.

Thanks!
--
Christian J.P. Flacco ~ CJFlacco@LBL.gov ~ 510.486.5451

http://www-physics.lbl.gov/~cflacco

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