From: mjs@hubcap.clemson.edu (M. J. Saltzman)
Newsgroups: sci.math
Subject: Re: >>n-dimensional Convex Hull algorithm?<<
Date: 5 Aug 96 15:27:29 GMT

mcg@mcg.math.waikato.ac.nz (Martin C. Glanvill) writes:

|Hi, I'm in (urgent) need of some C/C++ source for a n-dimensional Convex Hull 
|algorithm.

|Failing n-dimensional Convex Hull alg, does anyone know of the existence of
|a C/C++ alg for 4-D Convex Hull generation.

|Any pointers or direction to literature also gladly accepted... I have three 
|different algorithms for 3-D Convex Hull algs, but I'd rather not re-invent 
|the wheel if n-dimensional algs already exist (and work).

Check out the Linear Programming FAQ at
http://www.skypoint.com/subscribers/ashbury/linear-programming-faq.html
-- 
		Matthew Saltzman
		Clemson University Math Sciences
		mjs@clemson.edu

==============================================================================

From: orourke@grendel.csc.smith.edu (Joseph O'Rourke)
Newsgroups: sci.math,comp.graphics.algorithms
Subject: Re: >>n-dimensional Convex Hull algorithm?<<
Date: 6 Aug 1996 00:55:21 GMT

In article <4u3svr$ss2@thebes.waikato.ac.nz>,
Martin C. Glanvill <mcg@waikato.ac.nz> wrote:
>Hi, I'm in (urgent) need of some C/C++ source for a n-dimensional Convex Hull 
>algorithm.[...]
>Any pointers or direction to literature also gladly accepted... I have three 
>different algorithms for 3-D Convex Hull algs, but I'd rather not re-invent 
>the wheel if n-dimensional algs already exist (and work).

They exist and work and are available.  See the comp.graphics.algorithms
FAQ.  Re-inventing the wheel in this case would take you six months at the 
minimum, so check out the several pieces of code via
	http://www.geom.umn.edu/software/cglist
If you like what you find, complain to the US NSF for pulling the plug
on the Geometry Center.

==============================================================================

From: antoine.gautier@fsa.ulaval.ca (Antoine Gautier)
Newsgroups: sci.math
Subject: Re: Matrix Problem.  HELP
Date: 31 Aug 1996 22:38:49 GMT

whebert@digital.net (Wyck Hebert) wrote:
> I need help with the following problem...
> 
> "Find an N-by-N matrix of 0's and 1's with specified row, column, and 
diagonal 
> sums."

You can translate this into the set of constraints of an integer
linear problem (no objective function) and use any available code.
Expect to solve problems up to 50x50 in reasonnable time; In general,
your problem is NP-complete, unless some special structure can be
identified.

For more on integer problems, see e.g.
http://www.skypoint.com/~ashbury/linear-programming-faq.html

-------------------------------------------------------
  Antoine Gautier   (antoine.gautier@fsa.ulaval.ca)
-------------------------------------------------------
    Professeur, De'partement OSD 
    Faculte' des Sciences de l'Administration 
    Universite' Laval
    http://www.fsa.ulaval.ca/personnel/gautiera/