Re: [boost] Fixed point arithmetic - any interest?

From: Hervé Brönnimann (hervebronnimann_at_[hidden])
Date: 2007-04-22 00:25:07

On Apr 19, 2007, at 3:25 PM, Phil Endecott wrote:
> I'd also like to mention that I have been using this type to implement
> a 2D set<point> container using space filling curves.

This is highly interesting to me.  I suppose you're doing this for  
nearest neighbors of some kind.  You must be aware of  Timothy Chan's  
paper "Closest-point problems simplified on the RAM", in Proc. 13th  
ACM-SIAM Symposium on Discrete Algorithms (SODA), pages 472-473,  
2002.   I imagine (this was my first thought when reading Chan's  
paper) that everything can be wrapped into a functor that computes  
the order along the curve.  Is this the approach you're  
implementing?  I'd be interested to hear your thoughts / experience /  
esp. your setup (why you are interested in this in the first place).   
You can reply to the list if you think it's of general interest, or  
to me directly.

Re: the original topic of this thread, I really don't see the point  
of fixed-point arithmetic for this, though, it seems to me point  
coordinates could be computed in floating point, then rounded/scaled  
to integers for inserting into the set<point>.  Iow, the fixed-point  
coordinates are likely simply representational, not used in  
computations.  Unless you're dealing with moving points, and even  
then...

Btw, in Dr Dobb's I saw an article recently which I really didn't  
understand.  Seemed like the author rediscovered quad-trees.  Seems  
like a functor for comparing along space-filling curves would also  
make a great paper for Dr Dobb's / CUJ.  Cheers,
--
Herve Bronnimann