HI All, I agree with Jan that it would be good to use Hep3Vector to represent positions (although I think it is safe to assume that coordinates are cartesian unless stated otherwise).

It is important to understand that the overhead of List<Double> vs double[] can be astronomical in some cases, since you go from one object to N objects, with possible conversion to/from double<->Double and object creation on every use. I think this overhead really has to be evaluated on a case-by-case basis.

Tony

> -----Original Message-----
> From: [log in to unmask] 
> [mailto:[log in to unmask]] On Behalf Of 
> Tim Nelson
> Sent: Wednesday, July 27, 2005 12:43 PM
> To: Strube, Jan
> Cc: lcd-dev
> Subject: Re: Use of double[]
> 
> Hi Jan,
> 
> I will second that and go one further... I'd like to 
> encourage people  
> to use generic Java collections instead of arrays where 
> appropriate.   
> Except in the simplest cases, the additional power and 
> flexibility is worth the overhead.
> 
> Tim Nelson
> 
> On Jul 27, 2005, at 12:17 PM, Jan Strube wrote:
> 
> > Hi LCD Developers,
> >
> > I would like to encourage again the use of classes like 
> > SpacePoint/SpaceVector or HepVector.
> >
> > Let's look at the class Cluster.
> > It has a method double[] getPosition(). aha.
> > The javadoc says "Position of the cluster."
> > Not very helpful, the method name already states that.
> >
> > Now, the problem here is: what does this return ?
> > A three-dimensional cartesian vector ?
> > A three-dimensional cylindrical vector ?
> > A three-dimensional spherical vector ?
> > Just the two spherical angles ? Because after all, the radius is 
> > fixed...
> >
> > The second problem is this:
> > The cluster has a finite extension. How is this position defined ?
> >
> > The problem is that all of these things are obvious to the 
> developers 
> > of the class, but I don't think this is obvious to our 
> users. Please 
> > let's all try to make it easy on them. I am thinking primarily of 
> > graduate students like myself who may or may not know what they are 
> > doing.
> >
> >
> > Thank you,
> >     Jan
> >
> >
> > -- 
> > Jan Fridolf Strube                      University of Oregon
> >
> > Stanford Linear Accelerator Center
> >   mailstop 35
> >   bldg 48, rm 244
> >   phone: (650) 926-2913
> >
> >
> 
>