Fitting multiple subranges with user defined functions

Hi,
how can I use User Defined functions to fit datas on multiple subranges as described in the User Guide 5.14 in the Chapter "Fitting Histograms"?

I tried defining functions as described

Double_t moliere(Double_t *x,Double_t *par)
{

  Double_t arg = 0;
  if (par[2] != 0) arg = (x[0] - par[1])/par[2];   Double_t val = par[0]*TMath::Exp(-0.5*arg*arg);   return val;
}

Double_t ruth(Double_t *x, Double_t *par)
{

  Double_t val = par[0]/pow(sin((x[0]*TMath::PiOver2/180)-par[1]),4);   return val;
}

and in the main:

  ruthsx = new TF1("sx",ruth,mina,sx,2);   ruthsx->SetParameters(1,0);

  centro = new TF1("centro",moliere,sx,dx,3);   centro->SetParameters(maxc, 0, 1);

  ruthdx = new TF1("dx",ruth,dx,maxa,2);   ruthdx->SetParameters(1,0);

  total = new TF1("fit","ruth(0)+moliere(2)+ruth(5)",mina,maxa);

but when trying to launch it, it returns: Error in <TFormula::Compile>: Bad numerical expression : "ruth(0)" Error in <TF1::TF1>: function: fit/ruth(0)+moliere(2)+ruth(5) has 0 parameters instead of 1

thanks in advance
Gabriele Received on Wed May 16 2007 - 16:02:39 CEST