[ROOT] TLorentzVector

From: Ingo Strauch (strauch@toots.physik.rwth-aachen.de)
Date: Fri Jun 23 2000 - 14:16:43 MEST


Hi Rooters!

I've seen many requests for double precision fullfilled in the new ROOT
version, but I want to go the other way round:

Since ROOT 2.24/02 the TLorentzVector HAS A TVector3 and that means
sizeof(TLorentzVector) == 56 Bytes and when creating an object, 4 constructors
are called.

Since we want to store particles (containing a fourvector) in a micro-DST, the
TLorentzVector is sort of too big for our purposes. A fourvector class just
containing 4 datamembers (floats, we anyway don't need double precision) would
save 50% in size and number of constructor calls (and destructors, too...).

We of course could implement such a class ourselves, but I think it would be
better to have it as an official class (and maybe it is of general interest).

Cheers,
Ingo

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