Thank you for advice, but I have version 3.01/06, where this method doesn't work. This is a test: //file MyF.C float MyF(float x) { return x*x; } root> .L MyF.C root> h1->Draw("Eton","(Z1>0)*MyF(Eton)") *ERROR 26 : Unknown name : "MyF(Eton)" (Int_t)(-1) ============================================================== Dmitry A. Shtol (SND group) Budker Institute of Nuclear Physics On Wed, 6 Aug 2003, Rene Brun wrote: > Hi > > Using 3.05/07, create a file w.C as below > > //file w.C > double w(double z, double d, double sig) { > double s2 = sqrt(2)*sig; > return 0.5*(TMath::Erf((z+d)/s2-TMath::Erf((z-d)/s2)); > } > > then in ROOT, do > > root > .L w.C > root > ntuple.Draw("el11","(z>0)*w(z1m,10,5)"); > > Rene Brun > > > > On Wed, 6 Aug > 2003, Dmitry A. > Shtol wrote: > > > I asked this question some time before, but didn't get answer. I need > > to use user defined function as a weight in TNtuple::Draw(). In PAW it > > looks like that: > > > > app comis quit > > real function w(z,d,sig) > > real z,d,sig,s2 > > s2=sqrt(2.)*sig > > w=0.5*(erf((z+d)/s2)-erf((z-d)/s2)) > > end > > quit > > > > ************* > > > > nt/pro [id] [idn] el11 [cond]*w(z1m,10.,5.) > > > > Where el11 and z1m are elements of ntuple. > > What is the simplest way to do it in ROOT? > > > > ============================================================== > > Dmitry A. Shtol (SND group) > > Budker Institute of Nuclear Physics > > >
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