skid: A C repository from chreinhardt

				SKID (Spline Kernel Interpolative Denmax)
					
							VERSION 1.4.1


				A Group Finder for N-body Simulations

				Stadel Release 1.4.1: Dec. 2000

Changes from v1.1:
	o 	Fixed bug in tree building, this bug only affected cases where
		a very small "bucket" size was chosen and the number of particles
		was not a power of two.

Changes from v1.2:
	o	Added ability to handle moving both gas and dark particles since
		there seem to be situations where this is quite interesting.
	o	The -unbind option now works completely self consistently. It will
		now grab both the .grp and .gtp files, thereby getting the correct
		group center. If no .gtp file is present (as is the case when using 
		FOF) unbinding will calculate the group center to be the center of
		mass. This was somewhat of a disturbing problem in the past.
	o	No change log would be complete without this: enhanced performance.
		Tree searching has been improved so that moving particles is more 
		efficient. A "heuristic" algorithm is employed, by default, to remove
		scatterers which makes a big difference in the speed of the code.
		I add a conservative warning to this though, run a test case disabling
		the fancy remove scatterers algorithm first (-nsp) as a comparison.
		The reason for this is because we know this should usually be a good 
		technique, but we cannot prove that it will always be correct.

Changes from v1.3:
	o	Code is now much more modular and handles Lambda cosmologies.
	o	Standard TIPSY binaries are now used with the -std flag.

Version 1.4.1:
	o	Bug fix: don't set minimum scattering radius to fCvg. This
		is a very bad idea and leads to extremely bad performance 
		with large tau parameter. It is also not well motivated.

Included are:
	Makefile
	main.c
	kd.c
	kd.h
	grav.c
	grav.h
	smooth1.c
	smooth1.h
	tipsydefs.h
	totipnat.c
	dark.std
	demo
	man1/skid.1

For detailed information read the man page (either cat1/skid.1 or
man1/skid.1). A small demo of a 32768 particle input file has 
been included, just type demo after building skid. The demo input
is in the XDR standard binary format and is converted to a NATIVE
tipsy binary file by totipnat. The program totipnat is one of several
file conversion and other tools in a package called tipsy_tools which
is part of the TIPSY distribution.

To build:

	> make

To run the demo:

	> demo

To get further information contact:

	stadel@astro.washington.edu
chreinhardt/skid
