Dear Takefumi SORA,
I'm a ROOT user too, so I hope I will be able to give you some hints; as
far as I understood you would like to get the parameters of the fit of the
variable "leaf".
Looking at the prototype of the TTree::Fit method:
Int_t Fit(const char *funcname ,const char *varexp, const char
*selection,Option_t *option ,Option_t *goption,Int_t nentries, Int_t
firstentry)
it seems to me that its output is not a pointer to a TF1 object; this
means that it is not possible to use the line:
TF1 *fit0 = tree->Fit("gaus","leaf");
What I would do to reach your aim is first to try:
Double_t pedestal0 = gaus->GetParameter(1);
after the fit.
In case it didn't work, I'd try first to get the histogram to fit:
TH1F *hnew = new TH1F("hnew","hnew",#,#,#);
tree->Draw("leaf >> hnew");
and then fit it:
hnew->Fit("gaus");
After that, again:
Double_t pedestal0 = gaus->GetParameter(1);
Best regards
pietro
On Tue, 13 Aug 2002, Takefumi SORA wrote:
>Hi,Rooters
>
>I want to fit "Leaf" and get its parameter.
>This is my program.
>
> TFile *f = new TFile("381run.root");
> TTree *tree = (TTree*)f.Get("tree");
> tree->Fit("gaus","leaf");
> TF1 *fit0 = tree->Fit("gaus","leaf");
> Double_t pedestal0 = fit0->GetParameter(1);
> cout << pedestal0 << endl;
>
>Executing it, returned the error message.
>Error: Incorrect assignment to fit0, wrong type 'Int_t'
>
>How can I avoid the trouble ?
>
>--
>Takefumi SORA <tak-sora@bg7.so-net.ne.jp>
>
>
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