Hi Lorenzo,
Indeed I also want to optimise (when I'll find some time)
the Ali3Vector etc... classes for speed when no error propagation
is needed. What I am thinking of is to save the components and errors
separately in Double_t* and in additions etc... only go for the
error calculations if the error Double_t* is non-zero.
The other option is to save all components in one Double_t*
(or TArrayD) and check on the size (or introduce an internal flag/bit).
As I said when I would find some time I want to run some tests to see
what the gain might be and what is the most optimal way.
However, in case you have some ideas/suggestions, I would be happy
to hear them.
Cheers,
Nick.
> Dear Nick,
>
> Thank you very much for your comments.
> I had looked before to these AliROOT classes and the functionality
> that Ali3Vector and AliPosition provide in terms of reference frame
> is present in the new classes.
> In the new Vector classes it is possible as well to get functions (as
> distance) between two points even if the units are different like in
> AliPosition. For example you can do:
>
> XYZPoint p1;
> Polar3DPoint p2;
>
> XYZVector v = p1 - p2;
> double distance = v1.r();
>
>
>
> I have not put so far the functionality of built-in error
> propagation because it adds complexity to the class itself.
> It would increase the size of the Vector classes and in addition it
> would also penalize the performance of vector operations (like
> additions). And this probably it is probably not acceptable for some
> users which do not need this functionality.
>
> If this is considered to be useful, I think it could eventually be
> added as extra functionality to some additional classes (like
> VectorWithErrors) which would use the current Vectors.
>
> Cheers
>
> Lorenzo
>
> On 7 Jun 2005, at 09:38, Nick van Eijndhoven wrote:
>
> > Dear Lorenzo,
> > Maybe you could have a look at the AliRoot package as well at the
> > Alice CERN CVS repository.
> > In AliRoot/RALICE there exist already for quite some time the
> > classes Ali3Vector, Ali4Vector and AliPosition which basically
> > have the same functionality and also a built-in error access/
> > propagation procedure in case one performs operations with these
> > objects.
> > Maybe it would be nice to introduce in your classes (which will be
> > part of the standard ROOT 5 as far as I understand) also this error
> > handling facility.
> > Another item is that AliPosition allows to provide distances between
> > 2 locations even if the units used for the 2 locations are different.
> > This allows using data of different datasets/experiments.
> >
> > Cheers,
> > Nick.
> >
> > ----- Original Message -----
> > From: "Lorenzo Moneta" <Lorenzo.Moneta_at_cern.ch>
> > To: <roottalk_at_cern.ch>
> > Cc: "Andras Zsenei" <Andras.Zsenei_at_cern.ch>; "Mf Mf" <mf_at_fnal.gov>;
> > "Walter E Brown" <wb_at_fnal.gov>
> > Sent: Monday, June 06, 2005 10:51 AM
> > Subject: [ROOT] Proposal for new Physics Vector classes in ROOT
> >
> >
> >
> >> Dear ROOT users,
> >>
> >> This is a proposal describing new Physics Vector classes for 3D
> >> (geometrical Points and Vectors) and 4D (LorentzVectors) with their
> >> operations and transformations (rotations).
> >>
> >> The proposal is available, together with a prototype describing the
> >> API for the classes at
> >>
> >> http://seal.web.cern.ch/seal/MathLibs/GenVector/0-1-0/html/
> >> index.html
> >>
> >> These new classes will be part of the new mathcore package
> >> (part of libCore) and also available as a standalone library
> >> (libMathCore).
> >>
> >> The main characteristics as explained in the linked Web page are:
> >>
> >> -possibility to have Vector based on various coordinate systems
> >> such as Cartesian, Polar and Cylindrical
> >> -distinction between position vectors (Points) and displacement
> >> vectors
> >> -possibility to have classes based on arbitrary scalar type (they
> >> are templated on the scalar value type)
> >>
> >> An easy connection to Linear Algebra Vector and Matrices classes is
> >> also provided.
> >>
> >> The plan is to release a first version in the new ROOT version 5
> >> at the
> >> end of the month.
> >> The current Physics classes, TVector3, TLorentzVector, .. will be
> >> kept,
> >> and eventually they will be reimplemented using the new Vector
> >> classes
> >> (but still being back compatible).
> >>
> >> It is also planned to add to libMathCore other classes such as
> >>
> >> -Random number generators
> >> -Numerical algorithms such as adaptive integration,
> >> differentiation, root finders
> >> - Some basics mathematical functions
> >>
> >> In addition we will provide a libMathMore library with a more
> >> complete set of functions and algorithms
> >> based on the GNU GSL library.
> >>
> >> Any comments, or feedback or criticism is highly welcomed,
> >>
> >> Best Regards
> >>
> >> Lorenzo Moneta (on behalf of the ROOT Math Library Team)
> >>
> >>
> >
> >
>
Received on Tue Jun 07 2005 - 12:43:02 MEST
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