This is the ARPACK package from
http://www.caam.rice.edu/software/ARPACK/

Specifically the files are from
http://www.caam.rice.edu/software/ARPACK/SRC/arpack96.tar.gz
with the patch
http://www.caam.rice.edu/software/ARPACK/SRC/patch.tar.gz

The ARPACK README is at
http://www.caam.rice.edu/software/ARPACK/SRC/readme.arpack

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ARPACK is a collection of Fortran77 subroutines designed to solve large 
scale eigenvalue problems. 

The package is designed to compute a few eigenvalues and corresponding 
eigenvectors of a general n by n matrix A. It is most appropriate for large 
sparse or structured matrices A where structured means that a matrix-vector
product w <- Av requires order n rather than the usual order n**2 floating 
point operations. This software is based upon an algorithmic variant of the
Arnoldi process called the Implicitly Restarted Arnoldi Method (IRAM). When
the matrix A is symmetric it reduces to a variant of the Lanczos process 
called the Implicitly Restarted Lanczos Method (IRLM). These variants may be
viewed as a synthesis of the Arnoldi/Lanczos process with the Implicitly 
Shifted QR technique that is suitable for large scale problems. For many 
standard problems, a matrix factorization is not required. Only the action
of the matrix on a vector is needed.  ARPACK software is capable of solving
large scale symmetric, nonsymmetric, and generalized eigenproblems from 
significant application areas. The software is designed to compute a few (k)
eigenvalues with user specified features such as those of largest real part 
or largest magnitude.  Storage requirements are on the order of n*k locations.
No auxiliary storage is required. A set of Schur basis vectors for the desired
k-dimensional eigen-space is computed which is numerically orthogonal to working
precision. Numerically accurate eigenvectors are available on request. 

Important Features: 

    o  Reverse Communication Interface. 
    o  Single and Double Precision Real Arithmetic Versions for Symmetric,
       Non-symmetric, Standard or Generalized Problems.
    o  Single and Double Precision Complex Arithmetic Versions for Standard
       or Generalized Problems. 
    o  Routines for Banded Matrices - Standard or Generalized Problems. 
    o  Routines for The Singular Value Decomposition. 
    o  Example driver routines that may be used as templates to implement
       numerous Shift-Invert strategies for all problem types, data types
       and precision. 

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The ARPACK license is BSD-like.
http://www.caam.rice.edu/software/ARPACK/RiceBSD.doc

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Rice BSD Software License
Permits source and binary redistribution of the software ARPACK and
P_ARPACK  for both non-commercial and commercial use.

   Copyright (©) 2001, Rice University
   Developed by D.C. Sorensen, R.B. Lehoucq, C. Yang, and K. Maschhoff.
   All rights reserved.


   Redistribution and use in source and binary forms, with or without
   modification, are permitted provided that the following conditions are
   met:
    . Redistributions of source code must retain the above copyright notice,
      this list of conditions and the following disclaimer.
    . Redistributions in binary form must reproduce the above copyright
      notice, this list of conditions and the following disclaimer in the
      documentation and/or other materials provided with the distribution.
    . If you modify the source for these routines we ask that you change the
      name of the routine and comment the changes made to the original.
    . Written notification is provided to the developers of  intent to use
      this software.  Also, we ask that use of ARPACK is properly cited in
      any resulting publications or software documentation.
    . Neither the name of Rice University (RICE) nor the names of its
      contributors may be used to endorse or promote products derived from
      this software without specific prior written permission.


THIS SOFTWARE IS PROVIDED BY RICE AND CONTRIBUTORS "AS IS" AND  ANY  EXPRESS
OR  IMPLIED  WARRANTIES,  INCLUDING,  BUT  NOT  LIMITED  TO,   THE   IMPLIED
WARRANTIES OF MERCHANTABILITY AND  FITNESS  FOR  A  PARTICULAR  PURPOSE  ARE
DISCLAIMED. IN NO EVENT  SHALL  RICE  OR  CONTRIBUTORS  BE  LIABLE  FOR  ANY
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