Hi Victor, Maybe I am missing a point here, but the dotproduct you mention below has to my opinion no physical meaning and as such I would say should not be supported or at least the user should receive a warning message that he/she is doing nonsense. However, as I said I may be missing a point here and then I am saying nonsense. Cheers, Nick. Victor Perevoztchikov wrote: > > Hi Peter, > > but not between 3 and 4 Vectors. What would you expect to get as result > > of the scalar product between a 3-vector and a 4-vector ... > > It seems me it is evident. It must be used all possible information. > Si in the case of scalar product between a 3-vector and a 4-vector > must give scalar 3*3 > > Victor > > Peter Malzacher wrote: > > > > Hi Martin, hi Pasha, > > > > > inline void TLorentzVector::SetPPhiThetaM(Double_t p, > > > Double_t phi, > > > Double_t theta, > > > Double_t m) > > > { > > > // initialize vector with spherical coordinates > > > SetX(p * TMath::Cos(phi) * TMath::Sin(theta)); > > > SetY(p * TMath::Sin(phi) * TMath::Sin(theta)); > > > SetZ(p * TMath::Cos(theta)); > > > fE = TMath::Sqrt(p*p + m*m); > > > } > > > > I can implement setter functions in spherical coordinates, > > but I prefer to name it SetRhoPhiTheta. > > > > > I'd like to raise once again the issue of the relationship between > > > TLorentzVector and TVector3. I'm coming back to it every time I realize > > > that I can't do something as efficient and convenient as I'd like to. > > > > As announced some months ago we will cleanup the current implementation > > of TLorentzVecter when the corresponding classes of ZOOM and CLHEP will > > be merged. We will try to stay as close to their implementation as > > possible. > > The problem with inheriting from TVector3 occurs when one > > uses methods which meke sense between 3-Vectors or between 4-Vectors > > but not between 3 and 4 Vectors. What would you expect to get as result > > of the scalar product between a 3-vector and a 4-vector ... > > Therefore I think it is better to be explicit and get the 3-Vector > > component > > of a 4-Vector when you need it. Ok its slightly more inconvenient to > > type, > > but if one gets a const reference to an internal 3-Vector its as > > efficient as > > inheritance. > > > > Peter > > -- > Victor M. Perevoztchikov perev@bnl.gov perev@vxcern.cern.ch > Brookhaven National Laboratory MS 510A PO Box 5000 Upton NY 11973-5000 > tel office : 631-344-7894; fax 631-344-4206; home 631-345-2690
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