LDL Copyright (c) 2005-2011 by Timothy A. Davis.  All Rights Reserved.

LDL: a sparse LDL' factorization and solve package.
    Written in C, with both a C and MATLAB mexFunction interface. 

These routines are not terrifically fast (they do not use dense matrix kernels),
but the code is very short and concise.  The purpose is to illustrate the
algorithms in a very concise and readable manner, primarily for educational
purposes.  Although the code is very concise, this package is slightly faster
than the built-in sparse Cholesky factorization in MATLAB 6.5 (chol), when
using the same input permutation.

Requires UFconfig, in the ../UFconfig directory relative to this directory.

Quick start (Unix, or Windows with Cygwin):

    To compile, test, and install LDL, you may wish to first obtain a copy of
    AMD v2.0 from http://www.cise.ufl.edu/research/sparse, and place it in the
    ../AMD directory, relative to this directory.  Next, type "make", which
    will compile the LDL library and three demo main programs (one of which
    requires AMD).  It will also compile the LDL MATLAB mexFunction (if you
    have MATLAB).  Typing "make clean" will remove non-essential files.
    AMD v2.0 or later is required.  Its use is optional.

Quick start (for MATLAB users);

    To compile, test, and install the LDL mexFunctions (ldlsparse and
    ldlsymbol), start MATLAB in this directory and type ldl_install.
    This works on any system supported by MATLAB.

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LDL License:

    Your use or distribution of LDL or any modified version of
    LDL implies that you agree to this License.

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
    License as published by the Free Software Foundation; either
    version 2.1 of the License, or (at your option) any later version.

    This library is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public
    License along with this library; if not, write to the Free Software
    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301
    USA

    Permission is hereby granted to use or copy this program under the
    terms of the GNU LGPL, provided that the Copyright, this License,
    and the Availability of the original version is retained on all copies.
    User documentation of any code that uses this code or any modified
    version of this code must cite the Copyright, this License, the
    Availability note, and "Used by permission." Permission to modify
    the code and to distribute modified code is granted, provided the
    Copyright, this License, and the Availability note are retained,
    and a notice that the code was modified is included.

Availability:

    http://www.cise.ufl.edu/research/sparse/ldl

Acknowledgements:

    This work was supported by the National Science Foundation, under
    grant CCR-0203270.

    Portions of this work were done while on sabbatical at Stanford University
    and Lawrence Berkeley National Laboratory (with funding from the SciDAC
    program).  I would like to thank Gene Golub, Esmond Ng, and Horst Simon
    for making this sabbatical possible.  I would like to thank Pete Stewart
    for his comments on a draft of this software and paper.

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Files and directories in this distribution:
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    Documentation, and compiling:

	README.txt	this file
	Makefile	for compiling LDL
	ChangeLog	changes since V1.0 (Dec 31, 2003)
	License		license
	lesser.txt	the GNU LGPL license

	ldl_userguide.pdf   user guide in PDF
	ldl_userguide.ps    user guide in postscript
	ldl_userguide.tex   user guide in Latex
	ldl.bib		    bibliography for user guide

    The LDL library itself:

	ldl.c		the C-callable routines
	ldl.h		include file for any code that calls LDL

    A simple C main program that demonstrates how to use LDL:

	ldlsimple.c	a stand-alone C program, uses the basic features of LDL
	ldlsimple.out	output of ldlsimple

	ldllsimple.c	long integer version of ldlsimple.c

    Demo C program, for testing LDL and providing an example of its use

	ldlmain.c	a stand-alone C main program that uses and tests LDL
	Matrix		a directory containing matrices used by ldlmain.c
	ldlmain.out	output of ldlmain
	ldlamd.out	output of ldlamd (ldlmain.c compiled with AMD)
	ldllamd.out	output of ldllamd (ldlmain.c compiled with AMD, long)

    MATLAB-related, not required for use in a regular C program

	Contents.m	a list of the MATLAB-callable routines
	ldl.m		MATLAB help file for the LDL mexFunction
	ldldemo.m	MATLAB demo of how to use the LDL mexFunction
	ldldemo.out	diary output of ldldemo
	ldltest.m	to test the LDL mexFunction
	ldltest.out	diary output of ldltest
	ldlmex.c	the LDL mexFunction for MATLAB
	ldlrow.m	the numerical algorithm that LDL is based on
	ldlmain2.m	compiles and runs ldlmain.c as a MATLAB mexFunction
	ldlmain2.out	output of ldlmain2.m
	ldlsymbolmex.c	symbolic factorization using LDL (see SYMBFACT, ETREE)
	ldlsymbol.m	help file for the LDLSYMBOL mexFunction

	ldl_install.m	compile, install, and test LDL functions
	ldl_make.m	compile LDL (ldlsparse and ldlsymbol)

	ldlsparse.m	help for ldlsparse

See ldl.c for a description of how to use the code from a C program.  Type
"help ldl" in MATLAB for information on how to use LDL in a MATLAB program.