Hello Rooters, Concerning the discussion about modifications in TMath, I want to report about a problem I had recently. Try the following (in CINT or in compile mode, it does not matter) --> Double_t a = 1.0; --> Double_t b = 4.0e-16; --> a += b ; --> Double_t c = TMath ::ACos(a) c is now equal to -1.#IND. If you are a purist, you will say ok, nothing wrong, because the ACos of a value bigger than 1 does not make sense. But such a small error as 4.0e-16 is normal when calculating in double precision. So that it happens! For me, it happened when doing the scalar product of 2 unit vectors which were parallel. And it does not crash the program, but the program continues delivering wrong results! This is a nasty problem which obliged me to derive a new ACos (and ASin) function with protections. F.X.Gentit DAPNIA/SPP CEA Saclay http://gentit.home.cern.ch/gentit/
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