RE: Proposal for new Physics Vector classes in ROOT

Alan,

hmm, you are using there a very wide brush . There is the time spend calling the function and the time spend in the function .
If that ratio is unfavorable, you are right . However, if you have a function
that contains a little bit of beef , the picture looks of course different .

Eddy

• alan coelho <alan.coelho_at_attglobal.net> wrote:

> >- Throughout the code you are using templates (it's good and bad)
> > why not to use templates and class inheritance with method
> overloading
> > for classes like BasicLorentzVector, PositionVector3D etc. -
> > they are all "vectors" and should be derived from a single base
> class.
>
>
> Valeriy
>
> You are partly right. Code that contains inheritance and virtual
> functions are more flexible and easy to read than something like the
> STL.
>
> Virtual functions however cannot be inlined and this can result in a
> severe performance hit.
>
> Consider the simple loop:
>
>
> double s = 0.0;
> for (int i = 0; i < 1000000000; i++) {
> s += 1.0;
> }
>
> If you were to instead invoke a function call inside of this loop to
> do
> the add then this run around 6 times slower. If you had two
> unnecessary
> function calls (two adds) then it would run 12 times slower. If you
> made
> everything a function call then you would end up with interpreter
> speeds. There are ways of rearranging functons in memory to avoid a
> casche miss but this leads to more complications.
>
> Thus virtual function are nice but unfortunately we are tied to a
> physical world where hardware dictates how we write code.
>
> cheers
> Alan
>
>
>
>
>
>
> -----Original Message-----
> From: owner-roottalk_at_pcroot.cern.ch
> [mailto:owner-roottalk_at_pcroot.cern.ch] On Behalf Of Valeriy Onuchin
> Sent: Thursday, June 09, 2005 2:16 PM
> To: Lorenzo Moneta; roottalk_at_cern.ch; Andras Zsenei; Mf Mf; Walter E
> Brown
> Subject: Re: [ROOT] Proposal for new Physics Vector classes in ROOT
>
>
> Hi Lorenzo,
> this is my personal impression (ignore it).
>
> - First of all, the package lacks of "generality".
> Just glance at GenVector/GenVector/
> it contains too many (probably) "auxilary" classes like
> "EulerAngles", "CoordinateTraits" etc. why to show it to user?
>
> - Throughout the code you are using templates (it's good and bad)
> why not to use templates and class inheritance with method
> overloading
> for classes like BasicLorentzVector, PositionVector3D etc. -
> they are all "vectors" and should be derived from a single base
> class.
>
> - I do not see in the code *.cxx files. It is BAD to put the actual
> code only into header files.
>
> - totally the code contains ~2000 lines (without comments),
> most of them "just primitive assignments".
> This 2 days of work for professional programmer
> I'm afraid this is just another game which I/we saw at CERN for >10
> years
> LHC++, Objectivity, Anaphe, Aida, Pi, Seal, Spi ... GRID!!! ...
> repressing ROOT.
> Spent a lot of money (rougth estimates it's hundreds of millions
> of
> Euros) and
> efforts, conferencing in "exotic places" without any usable
> output.
>
> Regards. Valeriy
>
>
> Valeriy Onuchin wrote:
>
> > Hi Lorenzo,
> > as Linus Torvalds says - "show me the code".
> > Where can I find the latest sources of this library?
> >
> > Thanks. Regards. Valeriy
> >
> > Lorenzo Moneta wrote:
> >
> > > 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 Thu Jun 09 2005 - 19:51:25 MEST