Bug or feature in TTree::Draw()?

[Wile_E_Coyote]

Ah, this reminds me of a very old bug report …

TGraphSmooth::Approx bug in ROOT 5 and 6

I’ve spent quite a lot of time trying to understand why in some cases a TSpline5 created from a TGraphSmooth::Approx graph misbehaves around the maximal “x” value. In the end, I realized that there is a very nasty problem in TGraphSmooth::Approx (both ROOT 5 and ROOT 6 have the same problem). When the input parameter “xout = 0” (if “yright = rule = 0” or “rule = 1”), then: delta = (fMaxX - fMinX)/(fNout - 1); Later in the “for (Int_t i=0;i<fNout;i++)” loop: x = fMinX + i*delta; Due to “flo…