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  • Xpost from NaNet: NetLib news


    From: Eric Grosse
    Date: Sun, 19 Jul 92 22:51 EDT
    Subject: Netlib News: Searching for Files
    Sender: Numerical Analysis Digest (Vol. 92, Nr. 29, Sun, 26 Jul 92)

    In the last column (see SIAM News, November 1991), we saw that netlib had
    adapted to the growing size of program files by 1) providing access via ftp
    and xnetlib, 2) better mail splitting, and 3) user-specified mail limits.
    (Ftp is the Internet file transfer protocol and xnetlib is an X-windows
    program from Jack Dongarra's group using sockets for file transfer.)

    This time, we look at how netlib is adapting to the growing number of files.

    Recall that the organization of netlib is one of libraries and sublibraries,
    each described briefly in an ``index'' file. In the early days of netlib, you
    could download the dozen or so index files in areas of potential interest and
    keep the information at hand or in your head.

    By 1987 this was becoming more burdensome, so Greg Astfalk kindly prepared a
    keyword list. An email or xnetlib command like ``find bessel'' could quickly
    search for all related files in the collection.

    Keeping they keyword list up to date, however, quickly proved to be beyond our
    modest administrative resources. As time went by, the keyword list became
    less useful as it fell out of sync with the explosive growth in material.

    Since the index files are reliably updated, we've decided to keep the keyword
    information there. Moreover, to allow automatic searching, we've switched
    from the somewhat haphazard writing style formerly used to a more systematic
    syntax.

    Each file that you might want to request is now supposed to have a paragraph
    in the appropriate index file. Here's an example.

    file a/dloess
    for smoothing multivariate scattered data
    by Cleveland and Grosse
    ref Statistics and Computation 1:1
    prec double
    lang Fortran77
    gams L8h
    # The method is based on a moving
    # least squares fit by a quadratic,
    # accelerated by k-d trees and blending
    # functions. (To get the univariate
    # code, "send lowess from go".)

    The first line tells you how to get the file; say
    mail netlib@research.att.com
    send a/dloess
    or equivalently,
    send dloess from a.
    The next line provides a few keywords, and succeeding lines give more details
    about the program such as authors, literature reference, precision, language,
    and GAMS classification code. For a description of the complete scheme, ask
    netlib to
    send thesaurus gams from bib.

    So, as of June 1992, keyword searching again provides a comprehensive view of
    the collection. We are well aware that some searches don't lend themselves to
    a keyword approach, and we're exploring hierarchical classification (as in
    Boisvert et al. GAMS and in my approximation catalog). Other approaches are
    also being tried under the aegis of the HPCC (High Performance Computing and
    Communications) Software Sharing Initiative. We intend that the new index
    files will provide a sound database for these new user interface efforts.

    Turning now to another topic, it dismays me to report that some e-mail systems
    in the world still have trouble generating correct return addresses. The rule
    is that the program shipping mail to the outside world should be sure that
    there is a From: line in the header with a valid Internet address, not
    merely an abbreviation sufficient for the local campus. Sometimes, by
    carefully puzzling over other information in the header, a human can guess how
    to fix the address on failed mail. But netlib doesn't try to work miracles.
    If all else fails, you can resort to including in the main message text
    (before requests) the command
    path user@campus.edu
    (after substituting your own address).

    By the way, I have received several email messages of the sort ``why doesn't
    this silly netlib program ever respond to my mail?'', signed something like
    mystery-vax!joe. Unfortunately, if netlib can't get through to him, neither
    can I!

    Recent additions

    Quite a lot of material has been added since the last column. The big
    announcement, of course, is lapack, a successor to linpack and eispack. That
    has been covered elsewhere in the SIAM News and need not be dwelt on here.
    Similarly, there is a great deal of interesting material in the matlab
    libraries in netlib, but presumably matlab users will see descriptions in
    other newsletters.

    Traditionally all scientific computation was done in Fortran, but we're seeing
    more requests for library code in other languages, particularly C and C++.
    There are technical reasons (e.g. function pointers) and portability reasons
    behind this trend. For the most part, our community's approach has been to
    call from C main programs to Fortran library routines, or to apply the f2c
    Fortran-to-C translator. But native C libraries are appearing.

    One specific but outstanding example is David Gay's contribution, fp/dtoa.c.
    This contains C functions for perfect binary/decimal conversion. I use this
    for all my scientific computing input/output.

    A broader example is David E. Stewart's C library for matrix computations,
    meschach (pronounced ``me shark''). This provides the common operations on
    dense and sparse matrices, though of course is much smaller in scope than
    lapack. Readers interested in learning about the effect of dynamic memory
    allocation on library design might find this package illuminating.

    The operator overloading provided by C++ is attractive for matrix libraries,
    if implicit loop fusion is implemented cleverly. Various commercial efforts
    along these lines are contending; if someone cares to contribute a good,
    public-domain version to netlib, that would be welcome.

    Newcomers to C++ may be interested in James Coplien's Advanced C++ Programming
    Styles and Idioms, published by Addison-Wesley. For code, send index for
    c++/idioms.

    Algorithms from the new journal Numerical Algorithms are being archived in the
    numeralgo library. The first two entries are: ``na1'' (avoiding breakdown
    and near-breakdown in Lanczos type algorithms by Brezinski, Sadok, and Zaglia)
    and ``na2'' (B-nets of box splines on three- and four-directional meshes by
    M.-J. Lai)

    The library lp/generators contains transportation networks, assignment, and
    generalized network flow problems, from Darwin Klingman, Fred Glover, and M.
    Ramamurti.

    svdpack by Mike Berry computes singular values and singular vectors of large
    sparse matrices.

    misc/sparsdyn is a prototype sparse matrix algorithm development tool for Sun
    workstations. (T. A. Davis, and P.-C. Yew)

    misc/lalqmr is a package implementing the Freund, Gutknecht, and Nachtigal
    version of the look-ahead Lanczos algorithm. It includes driver code to
    compute eigenvalues of matrices, as well as a linear systems solver using the
    quasi-minimal residual method.

    misc/gemmw is a portable Level 3 BLAS implementation by Craig Douglas of
    Winograd's variant of Strassen's matrix multiply.

    The misc/mglab library provides a tutorial univariate multigrid program. The
    user may choose various multigrid cycles, transfer operators, smoothing
    methods, and nested iteration end defect correction. An Introduction to
    Multigrid Methods, Wiley, Chichester, 1992 by P. Wesseling.

    After a lapse, we're back on the toms (ACM Trans. on Math. Software)
    distribution, now complete through Collected Algorithm 702. See the journal
    for complete descriptions; a quick summary is:
    687: decision tree for initial value ode
    688: epdcol: a more efficient pdecol code
    689: nonlinear volterra integral equations of the second kind
    690: chebyshev polynomial software for elliptic-parabolic systems of pdes
    691: improving quadpack automatic integration routines
    692: model implementation and test package for the sparse blas
    693: floating point multiple precision arithmetic
    694: test matrices
    695: modified cholesky factorization
    696: inverse rayleigh iteration for complex band matrices
    697: univariate interpolation
    698: adaptive multidimensional integration for a vector of integrals
    699: Patterson's quadrature formulae
    700: Sturm-Liouville problems
    701: exact analysis of rectangular rank-deficient sparse rational linear systems
    702: truncated Newton

    Subroutines for maximum likelihood and quasi-likelihood estimation of
    parameters in nonlinear regression models by David Bunch, David Gay, and Roy
    Welsch have been submitted to TOMS. send index for opt/nlr for details.

    The libraries odrpack (orthogonal distance regression) and pppack (de Boor's
    Practical Guide to Splines) have been updated, and small changes made to
    napack, paranoia, picl, pltmg, pvm and others.

    If you're new to netlib, send e-mail containing the line ``help'' to one of
    the Internet addresses
    netlib@research.att.com
    netlib@ornl.gov
    netlib@nac.no
    netlib@draci.cs.uow.edu.au
    or uucp address uunet!research!netlib. A few minutes later, assuming you have
    speedy mail connections, you will receive information on how to use netlib and
    an overview of the many mathematical software libraries and databases in the
    collection.

    This column was written June 7, 1992.
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