I believe you're out of luck. TTreeFormula is for making selections on which events to draw, not as functions on the arguments themselves. In order to do this, you need to fill the histogram manually, i.e., for (int i = 0; i<30000; i++) { H1->Fill(Fun1(y),y); } H1->Draw(); The TTree::Draw() function is not intended for filling complicated histograms, but quickly viewing a simple plot. Cheers, Andy ---Dirk Meier <Dirk.Meier@cern.ch> wrote: > > > > Hello, > > I want to draw a function TF1 which gets its arguments from a TTree. > > s.th like this: > > { > TFile *f = new TFile("test.root"); // open file test.root > > TTree *t = (TTree*)f->Get("T"); // get the tree, > > TH1F *h1_1 = new TH1F("H1_1","H1_1",80,-0.1,1.1); // declare histogramm > > T->Draw("x>>H1_1","y<1 && y>0","",30000); // Draw values from > // tree into H1, x, y are floats in tree > > > TF1 *fun1 = new TF1("Fun1","pol7",0,1); // decleare a function > > H1_1->Fit("Fun1","","",0,1); // do a fit to the distribution of x > > // now I want to draw Fun1 as a function of y which is float in the tree > > // s.th like T->Draw("Fun1(y):y","y<1 && y>0","",30000); > > } > > > I believe TTreeFormula could help? > Does anybody has an example on how to use TTreeFormula > > > merci > > Dirk > > > > == Andrew Haas - haas@yahoo.com University of Washingon Physics Glast - D0 _________________________________________________________ DO YOU YAHOO!? Get your free @yahoo.com address at http://mail.yahoo.com
This archive was generated by hypermail 2b29 : Tue Jan 04 2000 - 00:34:37 MET