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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