LDL Copyright (c) 2005-2012 by Timothy A. Davis. http://www.suitesparse.com

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 SuiteSparse_config, in the ../SuiteSparse_config 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.suitesparse.com 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.suitesparse.com

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.