WCSLIB version 7.4 (2021/01/31)
-------------------------------

* C library

  - In wcshdo(), fixed a bug introduced in release 5.9 that potentially
    caused loss of numerical precision in the sprintf() formatting of
    floating point keyvalues.  This was triggered when a large range of
    CRPIXja, PCi_ja, or CDELTia values (as three separate groups) were
    formatted using an 'f' format descriptor, the range not being so
    large that it would have forced wcshdo() to revert to 'E' format.
    Reported by Mohammad Akhlaghi.

    Also in wcshdo(), fixed a bug introduced in release 7.1 that caused
    the coefficients of the TPD distortion function not to be written to
    the header.  TPD and Polynomial distortion function headers will now
    always include the DPja.DOCORR keyword.  Reported by Derek Homeier
    with patch.

  - In wcsset(), fixed a segv generated in attempting to report a non-
    standard units string with wcserr message reporting disabled.
    Reported by Mohammad Akhlaghi.

    In wcsutrne(), allow 'Angstroms' and 'angstroms' as additional
    synonyms for 'Angstrom'.

  - In datfix(), ensure that 0 is returned if an informational message
    is set in wcsprm::err.  Consequent on feedback independently from
    Mihai Cara and Bruce Merry.

    Clarified that informational messages may be set in wcsprm::err
    for returns of 0 from datfix(), obsfix(), unitfix(), and spcfix().

* User manual

  - Added cautions about translating CDi_ja to PCi_ja plus CDELTia for
    those historical distortion functions (TPV, TNX, ZPX) that expect to
    operate on intermediate world coordinates, rather than intermediate
    pixel coordinates.  Consequent on feedback from Mohammad Akhlaghi.

  - Documentation generation moved to doxygen 1.9.1 (was 1.8.19).


WCSLIB version 7.3.1 (2020/08/17)
---------------------------------

There are no functional changes in this release.

* C library
* Fortran wrappers
* PGSBOX
* Utilities

  - Changed all C code, including within the flex sources, Fortran and
    PGSBOX wrappers, and test suite, to use C99 style commenting (i.e.
    using //), excluding the header prologues used to generate the user
    manual.

* User manual

  - Documentation generation moved to doxygen 1.8.19 (was 1.8.18).


WCSLIB version 7.3 (2020/06/03)
-------------------------------

* C library

  - wcshdo() was writing MJD-OBS twice to the header, and MJD-BEG not
    at all.

  - In wcshdo(), if MJDREF assumes its default value, just write
    MJDREF = 0 (not MJDREFI & MJDREFF), and omit writing DATEREF,
    which, with a value of '1858-11-17', looks strange and is
    potentially confusing.  Reported by Thomas Robitaille.

    If the fractional part of MJDREF is zero, then just write the
    integer part as MJDREF (i.e. not as MJDREFI & MJDREFF).

  - Bug fix in wcsfix() - it was writing error messages that referred
    to DATE-REF and MJD-REF rather then DATEREF and MJDREF.  Reported
    by Mihai Cara.

  - Under control of a new flag, WCSHDR_DATEREF, added the option to
    wcspih() and wcsbth() to accept DATE-REF, MJD-REF, MJD-REFI,
    MJD-REFF, JDREF, JD-REFI, and JD-REFF as synonyms for the standard
    keywords, DATEREF, MJDREF, MJDREFI, MJDREFF, JDREF, JDREFI, and
    JDREFF.  The latter buck the pattern set by the other date keywords
    ({DATE,MJD}-{OBS,BEG,AVG,END}), thereby increasing the potential
    for confusion and error.

* Fortran wrappers

  - As compilers are becoming much stricter (gfortran 10), modified all
    Fortran test programs to use the type-specific equivalents of the
    various *PUT and *GET routines.  Reported by Ole Streicher.

  - For the fitshdr wrappers, added type-specific equivalents of
    KEYGET: KEYGTI, KEYGTD, and KEYGTC.

* PGSBOX

  - Modified pgtest to use the type-specific equivalents of WCSPUT.

* User manual

  - In the section "WCSLIB Fortran wrappers", promoted use of the type-
    specific equivalents of the various *PUT and *GET routines.

  - In the section "FITS-WCS and related software", added ASCL and ADS
    codes, where they exist, for all software packages mentioned.

  - Documentation generation moved to doxygen 1.8.18 (was 1.8.17).


WCSLIB version 7.2 (2020/03/09)
-------------------------------

* C library

  - In wcssub(), fixed a bug relating to handling coordinate lookup
    tables.  Reported by Mihai Cara with fix.

    Also increased the number of coordinate axes handled from 10 to 32.

* Installation

  - New configure option, --disable-shared, defeats generation of the
    sharable library.


WCSLIB version 7.1 (2020/01/01)
-------------------------------

Changes in the contents of the wcsprm struct necessitated incrementing
the major version number from 6 to 7 (i.e. the ABI changed).

* C library

  - In wcsset(), set wcsprm::mjdref[] to zero if neither it nor
    wcsprm::dateref are defined, as per the standard.  Reported by
    Thomas Robitaille.

    wcsset() now also checks that the number of coordinate axes does not
    exceed 32.

  - In tabs2x(), fixed an out-of-bounds array access produced by invalid
    world coordinates.  Reported by Mihai Cara and Michael Seifert.

    In tab.c, declare static three helper functions, tabedge(),
    tabrow(), and tabvox(), used by tabs2x().  Increased the number of
    coordinate axes handled by tabvox() from 16 to 32.

  - Extended datfix() to handle MJDREF/DATEREF, overlooked in the
    changes in release 6.1.  Also fixed the handling of MJD < 0.

  - Support Solar keywords RSUN_REF, DSUN_OBS, CRLN_OBS, CRLT_OBS,
    HGLN_OBS, and HGLT_OBS by accomodating them within an auxiliary
    struct, auxprm, within the wcsprm struct.  Now filled by the header
    parsers, wcspih() and wcsbth() and handled routinely by wcsinit(),
    wcssub(), wcscompare(), wcsfree(), wcsprt(), wcsset(), and wcshdo().
    Requested by Stuart Mumford (SunPy) with input from Bill Thompson.

  - Bug fix in wcsprintf_set() for resetting the output disposition.
    Reported by Mihai Cara with patch.

  - In dis.{h,c}, the DOCORR record is now handled as a first-class
    value via disprm::docorr.  This required changing the struct.

  - In cel.c, spc.c, wcserr.c, wcsfix.c, wcshdr.c, and wcsutil.c,
    quelled compiler warnings from gcc 9.2.0 generated by
    -Wmaybe-uninitialized and -Wstringop-truncation (via -Wall).

    Similarly for various programs in the test suite.

  - In various functions, quelled warnings from the Microsoft Visual C++
    compiler, mostly relating to pointer arithmetic.  Reported by
    Michael Seifert.

* Fortran wrappers

  - Handled compiler warnings from gcc 9.2.0 generated by
    -Wstringop-truncation (via -Wall).

  - Minor enhancements to character argument handling, including, in
    prjget_(), blank-filling the returned strings matching PRJ_CODE and
    PRJ_NAME, and likewise for SPC_TYPE and SPC_CODE in spcget_().

* Utilities

  - In wcsgrid, handled compiler warnings from gcc 9.2.0 generated by
    -Wstringop-truncation (via -Wall).

* User manual

  - In the section on "FITS-WCS and related software", added mention of
    the R wrappers (Rwcs).  Suggested by Aaron Robotham.

  - Added a new section detailing the limit on the number of image axes
    that WCSLIB can handle (currently 32), and how this could be
    increased if needed.  Prompted by Thomas Robitaille.

  - Augmented the section on the Fortran wrappers, particularly with
    respect to character string handling in argument lists.

  - Documentation generation moved to doxygen 1.8.17 (was 1.8.16).


WCSLIB version 6.4 (2019/08/15)
-------------------------------

* Installation

  - The rule change to the Fortran makefile in v6.3 to add getwcstab_f.o
    to the sharable library causes it to depend on CFITSIO to resolve
    fits_get_wcstab().  Hence backed out of that change.

* User manual

  - Documentation generation moved to doxygen 1.8.16 (was 1.8.14).


WCSLIB version 6.3 (2019/07/12)
-------------------------------

* C library

  - Fixed the Polynomial and TPD distortions so that, as stipulated in
    WCS Paper IV, they are now considered to return an additive
    correction to be applied to the given coordinates, rather than the
    corrected coordinates themselves.

    Added a new subsection to the prologue of dis.h entitled 'Historical
    idiosyncrasies', which discusses this issue and other vagueries.

    Amended components of the test suite accordingly: SIPTPV.keyrec,
    TPV7.keyrec, and tdis1.c.

  - Fixed memory leaks and other potential problems that arose in the
    wcserr system consequent on changes made in release 6.1.

    Memory allocated by wcsfixi() for messages in the array of wcserr
    structs must now be freed by the caller.  Amended twcsfix.c
    accordingly.

  - Plugged memory leaks arising in disset().

  - New function wcsdealloc() provided to free memory allocated within
    certain WCSLIB routines.  Suggested by David Motl.

  - Eliminated a swag of inconsequential compiler warnings, particularly
    those emanating from the flex sources.

* Validation

  - The library, Fortran wrappers, utilities, and test programs now pass
    runtime analysis using -fsanitize=address and -fsanitize=undefined
    in gcc 8.3.0, in addition to valgrind.  Also compile-time strictures
    using -std=c99, -pedantic, -Wall, -Wextra, and -DFORTIFY_SOURCE=2.
    Prompted by feedback from Ole Streicher.

* Installation

  - The non-graphical tests now run reliably in parallel builds
    (make CHECK=nopgplot -j8 check).  Requested by Mohammed Akhlaghi.

    The graphical tests can also be run in parallel, but as PGPLOT can
    only handle one stream at a time, some graphics are likely to be
    lost.  Nevertheless, it is a useful option, especially with runtime
    analysis via -fsanitize=address, etc.

  - As CFITSIO doesn't provide a Fortran wrapper for fits_read_wcstab(),
    getwcstab_f.o is now always included in the WCSLIB object library
    and sharable library if CFITSIO is available (and the WCSLIB Fortran
    wrappers are required).  Use 'configure --without-cfitsio' to
    defeat this.

  - Tidied up some aspects of the build where CFITSIO is not available.

* User manual

  - Fixed minor formatting problems in dis.h.


WCSLIB version 6.2 (2018/10/20)
-------------------------------

* C library

  - Consequent on the change in release 6.1, reapplied soothing balm to
    the wtbarr struct definition in wcs.h for C++ compilation (C and
    Fortran compilation being unaffected).  While the object libraries
    themselves are unchanged, the modified wcs.h must be installed for
    compiling C++ applications.  Reported by Corentin Schreiber.

* User manual

  - Fixed minor formatting problems with the doxygen manual generation.


WCSLIB version 6.1 (2018/10/19)
-------------------------------

* C library

  - Added support for time-related WCS keywords (Paper VII) by expanding
    the wcsprm struct to store them as auxiliary values, now filled by
    the header parsers, wcspih() and wcsbth() and handled routinely by
    wcsinit(), wcssub(), wcscompare(), wcsfree(), wcsprt(), wcsset(),
    and wcshdo().

  - Augmented datfix() to do various consistency checks on the new
    time-related keyvalues, and added a new routine, obsfix(), to check
    consistency of the OBSGEO-[XYZLBH] observatory coordinates.

  - In the usage notes for wcsbth(), clarified that, according to WCS
    Papers III and VII, certain global image header keywords are
    permitted in binary table headers and are expected to be inherited
    by image arrays and pixel lists, and elaborated on the difficulties
    that such inheritance may cause for pixel lists.

  - Revamped message string handling in the wcserr module to allow
    arbitrarily long messages while greatly reducing the sizeof the
    struct.

  - Extracted the definition of the wtbarr struct from wcs.h to a
    separate header file, wtbarr.h, in order to reduce the number of
    irrelevant warnings generated by 'gcc -Wpadded' (primarily for
    code development).  Applications code that needs to access members
    of the struct (unlikely) must now include wtbarr.h (or wcslib.h).

  - The WCSLIB major version number was incremented as changes to the
    wcsprm struct makes the ABI of the sharable library incompatible
    with executables linked with that of older releases.

* Fortran wrappers

  - Match changes to the C library, including adding a wrapper for
    obsfix().

* Installation

  - Several changes to configure and the makefiles aimed at facilitating
    code development.


WCSLIB version 5.20 (2018/10/05)
--------------------------------

* C library

  - Added utility functions dpkeyi() and dpkeyd() to dis.c, and removed
    the corresponding functions from wcsutil.c.

* Fortran wrappers

  - New wrappers for dpkeyi() and dpkeyd().

* Installation

  - Reworked the makefiles to allow parallel library builds, as required
    by some software distributions.  Reported by Dustin Lang with
    suggested patch, and Zaak Beekman.  (Parallel execution of the test
    suite is not supported.)

  - The introduction of "deterministic" archiving (ar(1)) broke
    dependency analysis in the WCSLIB makefiles on the many systems
    where it is now enabled by default (i.e. binutils configured with
    --enable-deterministic-archives).

    Modified configure to force non-deterministic archiving during the
    library builds, thus repairing the dependency analysis.  However,
    the static object libraries are now reconstructed using
    deterministic archiving in the process of installing them.

  - Fixed problems with the dependency analysis, solely affecting code
    development.


WCSLIB version 5.19.1 (2018/07/28)
----------------------------------

* Installation

  - Updated ./config/config.{guess,sub} to the latest versions from the
    GIT repository, timestamped 2018-07-18 and 2018-07-25, respectively.
    The previous pair were dated 2012-02-10 and 2012-04-18.


WCSLIB version 5.19 (2018/07/27)
--------------------------------

* C library

  - In wcssub(), fixed a bug in handling distortion functions on axes
    with changed axis number in the subimage (i.e. via deletion or
    addition of an axis).

  - In various routines within dis.c, wcs.c, wcshdr.c, and wcspih.l,
    increased the size of various sprintf() output buffers to avert
    -Wformat-overflow warnings from gcc 8.1.0 (with -DFORTIFY_SOURCE=2).
    Reported by Simon Conseil.

    Also fixed other warnings in these routines from gcc 8.1.0
    relating to -Wcast-function-type, -Wmaybe-uninitialized, and
    -Wunused-parameter.

  - In wcsutrn.l (the units alias translator used by wcsfix), recognise
    'Deg', 'Degree', and 'Degrees' as aliases for 'deg'.  Rogue header
    reported by Jim Lewis.

  - Added a note to the prologue of spx.h explaining WCSLIB's use of
    Cox's air-to-vacuum transformation equation rather than the IUGG
    relation cited in WCS Paper III.  Noted by Benjamin Alan Weaver.

  - In the test suite, avert nuisance compiler warnings in tdis1.
    Made tsphdpa more robust in handling user coordinate input.

* PGSBOX

  - In pgwcsl_(), avert nuisance warnings from gcc 8.1.0 relating to
    unused parameters (-Wunused-parameter).  Also averted nuisance
    compiler warnings in cpgtest.

* Utilities

  - wcsware was not reading the -TAB table from the FITS file for
    alternate descriptions, bug reported by Chiara Marmo.  Nor was
    wcsfix() ever invoked for them.

    Made it more robust in handling user input of coordinates for the
    -x and -w options.

  - Fixed compiler warnings from gcc 8.1.0 in HPXcvt
    (-Wmaybe-uninitialized), and wcsgrid (-Wformat-overflow).

* Installation

  - Amended configure.ac to allow cross-compilation, and also updated
    the auxiliary configure scripts in the config/ directory.  Patch
    supplied by Mos Giordano.


WCSLIB version 5.18 (2018/01/10)
--------------------------------

* C library

  - New routines introduced to preclude altering the global variables
    NPVMAX, NPSMAX, and NDPMAX, which determine how much memory to
    allocate for storing PVi_ma, PSi_ma, DPja, and DQia keyvalues:
    wcsinit(), lininit(), lindist(), and disinit().  These are now used
    by various WCSLIB routines, such as the header parsers, which
    previously temporarily altered the global variables, thus posing a
    thread hazard.  Testing and feedback on thread-safety issues, with
    patches, from Rodrigo Tobar Carrizo.

  - The Flex scanners, fitshdr(), wcsbth(), wcspih(), wcsulexe(), and
    wcsutrne(), have been rewritten as thin wrappers (with the same API)
    over scanners that were modified (with changed API) as required to
    use Flex's "reentrant" option.  Consequently, they are now reentrant
    and should be thread-safe.  That also passes through to the
    deprecated wrappers, wcsulex() and wcsutrn().

  - Fixed memory leaks in lindist() and lincpy() uncovered by valgrind.

  - Test programs tfitshdr, tpih1, tpih2, and ttab3 are now careful to
    free all allocated memory before exit to defeat spurious reports of
    memory leaks by valgrind.

* Fortran wrappers

  - New wrappers for wcsinit(), lininit(), lindist(), and disinit().

* Installation

  - configure now recognises the value of ARFLAGS obtained from the
    environment.

* User manual

  - Updates and amendments in line with the above changes.

  - Documentation generation moved to doxygen 1.8.14 (was 1.8.13).


WCSLIB version 5.17 (2017/09/18)
--------------------------------

* C library

  - Fixed a memory leak in wcspih().  Reported by Pim Schellart.

  - Fixed compiler warnings about comparison between signed and unsigned
    integers in tab.c (Pey-Lian Lim).  Also fixed warnings in other
    functions about unused parameters.

* Fortran wrappers

  - Fixed compiler warnings about comparison between signed and unsigned
    integers in several routines.

* PGSBOX

  - Fixed a compiler warning about comparison between signed and
    unsigned ints.

* Installation

  - Removed setgid permission on installation directories (for Fedora
    Linux, reported by Sergio Pascual).

* User manual

  - Minor updates and amendments.

  - Documentation generation moved to doxygen 1.8.13 (was 1.8.10).


WCSLIB version 5.16 (2017/01/15)
--------------------------------

* C library

  - Bug fix in spcfix() for the previous change.  Reported separately by
    Julian Taylor & Peter Williams.


WCSLIB version 5.15 (2016/04/05)
--------------------------------

* C library

  - Bug fix in wcsulex.l for the previous change.  Reported, and fix
    supplied by Tammo Jan Dijkema.

  - In spcfix(), report the value of VELREF if ctype is translated from
    the AIPS convention.


WCSLIB version 5.14 (2016/02/07)
--------------------------------

* C library

  - In wcsulex.l and wcsutrn.l, applied a workaround for a memory leak
    introduced by a change (bug) in flex in Aug/2012.  Reported, and
    fix supplied by Thomas Robitaille and Erik Bray.

* Installation

  - In MacOSX, create symlink libwcs.dylib pointing to the dynamic
    library so that WCSLIB is linked dynamically by default.  Requested
    by Paul Price.


WCSLIB version 5.13 (2016/01/26)
--------------------------------

* C library

  - In wcshdo(), provide floating-point format control via the 'ctrl'
    argument (formerly 'relax').

  - In wcspih(), PLATEID by itself is no longer sufficient to trigger a
    DSS translation (reported by James Allen).

  - In unitfix(), ensure that the message buffer cannot be overrun, e.g.
    by blank-padded unit strings (reported by Vishal Kasliwal).


WCSLIB version 5.12 (2015/11/15)
--------------------------------

* C library

  - Bug fix in wcshdo() for CRVALia precision reported by Mihai Cara.


WCSLIB version 5.11 (2015/10/18)
--------------------------------

* C library

  - Bug fixes in wcspih.l and dis.c for WAT distortions provided by
    Ole Streicher.


WCSLIB version 5.10 (2015/10/09)
--------------------------------

* C library

  - In wcshdo(), allow output of floating point keyvalues to 15
    significant digits (was 14), mainly for astropy.

  - In wcspih(), allow unrecognised WAT projection types (tan, etc.) to
    pass without returning an error.  Reported by Michael Droettboom.
    Also fixed a bug triggered by SIP keywords in unconventional order,
    reported by Colin Slater, LSST.


WCSLIB version 5.9 (2015/07/21)
-------------------------------

* C library

  - In disx2p(), make proper allowance for the possibility that the TPD
    and SIP forward and inverse distortion polynomials may not be of the
    same degree, reported by Martin Kuemmel.

  - Fix-ups in wcshdo() reported by Michael Droettboom, and several
    tidy-ups as well.


WCSLIB version 5.8 (2015/07/08)
-------------------------------

* C library

  - DSS (Digitized Sky Survey) coordinates are now handled via TPD, as
    are the TNX and ZPX "projections".  New test script tdis3 and
    headers DSS.keyrec, TNX.keyrec, and ZPX.keyrec.

  - New function dishdo() can be used to set a flag that causes
    wcshdo() to write headers in the form of the distortion function
    used internally (usually TPD).

  - Added the capability, via DPja.DOCORR, for a distortion function to
    to compute an additive correction to the undistorted coordinates
    (rather than computing the distorted coordinates themselves).

  - Added auxiliary variables to TPD via DPja.AUX.jhat.COEFF.m.

  - Bug fix in wcshdo() for TPV, diagnosed by Michael Droettboom.

* Fortran wrappers

  - Wrapper for dishdo().


WCSLIB version 5.7 (2015/06/29)
-------------------------------

* C library

  - Extended wcssub() to handle distortions (and thus wcscopy() also).
    This required axis mapping to be enabled for SIP distortions within
    WCSLIB.

  - wcshdo() now handles all distortions currently supported by WCSLIB:
    SIP, TPV, TPD, and Polynomial.

  - Bug fixes in sphx2s() and sphs2x() for non-unit vector strides for
    special-case rotations.

  - In wcsset(), modify wcsprm::ctype after translating TPV so that
    subsequent calls won't try to re-translate it, the PVi_ma records
    by then having been erased.  Reported by Michael Droettboom.  Also,
    restore NDPMAX after translating TPV.

  - Bug fixes in discpy(), disprt(), disset(), and disx2p().

  - Added disperr(), prjperr(), spcperr(), spxperr(), and tabperr() to
    complete the set and make reporting errors slightly more convenient.

* Utilities

  - wcsware has a new option, -o, to print the wcsprm struct in the form
    of a FITS header using wcshdo().  Also, the -a option has been
    extended to allow a 0-relative numeric index for selecting an
    alternate WCS, where the alternates are sequenced alphabetically
    (without gaps) following the primary representation.

* User manual

  - Documentation generation moved to doxygen 1.8.10 (was 1.8.9.1).


WCSLIB version 5.6 (2015/06/14)
-------------------------------

* C library

  - Bug fixes in wcspih() and sipset() to account for the fact that the
    independent variables of the SIP polynomial are pixel coordinate
    offsets from CRPIXja, not pixel coordinates per se.  Diagnosed by
    Michael Droettboom.

    Validated SIP and TPV handling by comparing the output of
    'wcsware -x' with that of wcstools 'xy2sky -d -n6' using astropy's
    SIP test headers, and separate SIP and TPV headers originating from
    the Palomar Transient Factory provided by David Shupe.

    Changed SIP.keyrec so that CRPIX1 and CRPIX2 differ in value,
    thereby making tests sensitive to any confusion between the two.


WCSLIB version 5.5 (2015/05/05)
-------------------------------

* C library

  - Bug fixes in wcspih.l for headers with multiple distortions, and for
    distortion parameter look-alike keywords.

  - Bug fix in sipset() uncovered by valgrind.


WCSLIB version 5.4.1 (2015/05/01)
---------------------------------

* C library

  - Added a fairly lengthy section to the prologue of dis.h describing
    the Paper IV keywords and the distortion functions currently
    implemented.

* User manual

  - Added a new section on WCSLIB version numbers.


WCSLIB version 5.4 (2015/04/21)
-------------------------------

* C library

  - Further work on distortions: wcspih() now parses Paper IV distortion
    keywords (CPDISja, CQDISia, DPja, DQia, etc.), thus handling record-
    valued keywords.  SIP keywords are also parsed and translated into
    Paper IV keywords.

  - TPV, SIP, and whereever possible, the general Polynomial distortion
    function of Paper IV are now implemented by the Template Polynomial
    Distortion (TPD), that being a superset of TPV and SIP.  TPD, which
    can also handle 1D distortions and be used for inversions, is also
    supported as a separate distortion type defined by Paper IV
    keywords.  TPD efficiently handles 1D distortions and distortions
    without radial terms.

  - Specialized inverse distortions, such as defined by SIP, are
    implemented by TPD and recognized by disx2p(), which uses them to
    compute the initial approximation of its more precise iterative
    solution.

  - Generalized tdis1.c so that it can do closure tests for SIP headers,
    and added a SIP test header.


WCSLIB version 5.3.1 (2015/04/21)
---------------------------------

* C library

  - Bug fix in test program tdis1.c reported by Martin Kuemmel.


WCSLIB version 5.3 (2015/04/21)
-------------------------------

First public release of WCSLIB 5.x with distortions capability.

* C library

  - Changed disprm::dtype from char[16] to char[72] for reasons relating
    to header parsing.

  - More armour plating for disset() and friends.  They also use new
    utility functions wcsutil_dpkey_int() and wcsutil_dpkey_double() to
    extract numeric values from a dpkey struct.  This ensures their
    independence of the data type, the appropriate reporting of dpkey
    values by disprt(), and (eventually) the appropriate writing of DPja
    and DQia keyvalues by wcshdo().

  - Augmented the usage comments for dpfill() to explain how numeric
    values in a dpkey struct are handled.

* Utilities

  - wcsware now uses wcserr to provide a backtrace on errors.  Also
    fixed a couple of minor annoyances relating to alternate
    representations.


WCSLIB version 5.2 beta release (2015/04/15)
--------------------------------------------

* C library

  - Further development of disprm and related functions to implement
    the FITS keywords for distortions introduced in WCS Paper IV, thus
    changing disprm's ABI once again.

    disprm's model is now similar to wcsprm's handling of PVi_ma and
    PSi_ma, where the parsed keyrecords are loaded into a set of pvcard
    and pscard structs and wcsset() does the analysis.  For disprm, the
    parsed DPja or DQia keyrecords are loaded into a set of dpkey
    structs for disset() to analyse.

  - New function dpfill() aids in filling a dpkey struct.  Function
    disparms() has been removed.  It was no longer needed as
    disprm::parms[][] is now a "returned" member of the struct.

  - Implementation of the general Polynomial distortion function defined
    in Sect. 3.1 of WCS Paper IV.  The polynomial is defined in terms of
    Paper IV keywords.

  - Bug fixes in diswarp() and linwarp() reported by
    Michael Droettboom.

  - Test program tdis1 now tests a TPV header for closure in two ways:
    directly as a specialist TPV distortion (as before), then by
    translating it into a general polynomial distortion.  It then also
    tests that the TPV and polynomial distortions produce the same
    results.

* Fortran wrappers

  - Changes to the wrappers reflecting changes to disprm.

  - Bug fixes in fitshdr_f.c, and test programs tdis1.f, tfitshdr.f,
    twcsfix.f, and twcs.f.  All reported and/or fixed by Ole Streicher.


WCSLIB version 5.1 beta release (2015/04/07)
--------------------------------------------

* C library

  - Distortions-related bug fixes to linset(), linp2x(), and linx2p().

  - New functions diswarp() and linwarp() compute statistics of the
    distortion functions over a specified domain.  Changed tdis1.c to
    test them.

  - Changes to disprm (so changed ABI).

* Fortran wrappers

  - Wrappers for diswarp() and linwarp().


WCSLIB version 5.0 beta release (2015/04/05)
--------------------------------------------

* C library

  - Implemented the framework of WCS Paper IV (the draft distortions
    proposal) based on a new struct, disprm, and suite of routines with
    header dis.h: disini(), disalloc(), discpy(), disfree(), disprt(),
    disset(), disp2x(), and disx2p().  New test program tdis1.

    Consequent changes to the linprm struct have altered its ABI, thus
    necessitating an increment in the WCSLIB major verion number.

  - wcsset() now recognises the "TPV" projection proposed in an early
    draft of WCS Paper II, and translates it into a disprm distortion -
    by request of Octavi Fors.  Additionally, it recognises "TPU" as
    equivalent to "TPV" but using a prior distortion (coming before the
    linear transformation matrix) rather than sequent (coming after it).

  - In wcspih() and wcsbth(), added relaxation flags to allow PC0i_0ja,
    PV0j_0ma, and PS0j_0ma (i.e. with leading zeroes on the index).

  - Added wcslib_version() to return the WCSLIB version number, as
    suggested by Ole Streicher.

  - Fixed problems uncovered by valgrind in prjbchk() (reported by
    Ger van Diepen), sphx2s(), sphx2s(), spcspxe(), spcxpse(), tabini(),
    and wcshdo_util().

  - Tidied up error reporting, particularly relating to translating
    status returns from lower-level functions.  New functions linperr()
    and celperr() report error messages from the structs they contain
    in addition to their own.

  - Changed output formatting of floating point values in linprt(),
    celprt(), prjprt(), spcprt(), tabprt(), and wcsprt().  Updated the
    test output reference files for tbth1, tpih1, twcsfix, twcssub, and
    twcstab to suit.

  - Tidied up several of the test programs, mostly to free memory
    explicitly before exit so that valgrind doesn't report (non-)leaks.

* Fortran wrappers

  - Wrappers for the new distortion functions.  New test programs
    tdis1.f and tdis2.f.

  - Updates following changes to wcspih() and wcsbth().

  - Added wrappers for linperr() and celperr().  Also added prjperr_(),
    spcperr_(), and tabperr_() as convenient wrappers on wcserr_prt().

  - Wrapper for wcslib_version().

* Utilities

  - Added a "lint" function to wcsware to check a FITS header for
    conformance to the WCS standard.  New test program twcslint.

* PGSBOX

  - In PGCRLB, fixed an incorrect use of the MOD intrinsic reported by
    'gfortran -std=f95' via Jean-Baptiste Marquette.


WCSLIB version 4.25.1 (2015/01/05)
----------------------------------

* C library

  - Updated the test output reference files for tpih1, tbth1, twcsfix,
    and twcstab to account for the change to wcsset() in release 4.25.

* Fortran wrappers

  - Updated the test output reference files for tpih1, twcsfix, and
    twcstab to account for the change to wcsset() in release 4.25.

* User manual

  - Documentation generation moved to doxygen 1.8.9.1 (was 1.8.8).


WCSLIB version 4.25 (2014/12/15)
----------------------------------

* C library

  - wcsset() now supplies default values for the auxiliary keywords
    EQUINOXa and RADESYSa if not present in the FITS header.


WCSLIB version 4.24 (2014/09/19)
----------------------------------

* C library

  - Changed API to wcscompare() to allow a tolerance to be specified for
    floating-point comparisons.  Contributed by Michael Droettboom.

* Fortran wrappers

    Track the change to wcscompare().

* User manual

  - Documentation generation moved to doxygen 1.8.8 (was 1.8.4).

  - Added mention of WCSLIB in "homebrew-science" (MacOSX) in the
    section on other packages.


WCSLIB version 4.23 (2014/05/11)
--------------------------------

* C library

  - New function wcscompare() compares two wcsprm structs for equality
    with varying degrees of strictness.  Test program twcscompare.
    Contributed by Michael Droettboom.

  - In wcssub(), fixed a bug uncovered by valgrind arising from
    allocation of insufficient memory for temporaries when a new axis
    is added.  Reported by Michael Droettboom.

  - In wcshdo(), don't write RESTFRQ or RESTWAV if zero.

    Also, to distinguish them from integer keyvalues, floating-
    point values will now always be written with an exponent or
    fractional part, ".0" being appended if necessary to achieve this.
    Suggested by Peter Weilbacher.

  - Fixed the '-h' option in twcshdr.

* Fortran wrappers

  - Wrapper for wcscompare().


WCSLIB version 4.22 (2014/04/13)
--------------------------------

* C library

  - In pcox2s() and pcos2x(), use alternative projection equations for
    greater numerical precision near theta == 0.  In cops2x(), return
    an exact result for theta at the poles.  Relaxed the tolerance for
    bounds checking a little in sflx2s().


WCSLIB version 4.21 (2014/03/24)
--------------------------------

* C library

  - New function prjbchk() performs bounds checking on native spherical
    coordinates.  It is invoked automatically by the deprojection (x2s)
    routines if prjprm::bounds&4 is set.  Documented the new bounds
    checking implemented by prjbchk() in the prologue entry for
    wcsbchk().  Improvements to tprj1 to test the vector API of prjx2s()
    and to deal better with out-of-bounds native coordinates returned by
    it.

  - Bug fixes in the projection routines: in hpxx2s() relating to bounds
    checking, bug introduced at 4.20, reported by Michael Droettboom; in
    parx2s() and molx2s() relating to setting the stat vector; in
    hpxx2s() relating to implementation of the vector API; and in
    xphx2s() relating to setting an out-of-bounds value of phi.

* Fortran wrappers

  - Wrapper for prjbchk().  Modified tprj1.f to track changes to the C
    version.


WCSLIB version 4.20 (2013/12/18)
--------------------------------

* C library

  - New function, wcsbchk(), for controlling bounds checking in the
    projection routines.

  - Enable bounds checking in the pixel-to-sky (x2s) direction for HPX
    and XPH if prjprm::bounds&2.  Tightened bounds checking in xphx2s().
    prjini() now sets prjprm::bounds = 3 to enable all bounds checking
    by default.

  - Fixed an incorrect error message in wcs_units().  Also report
    potentially unsafe units translations in unitfix() - both
    contributed by Michael Droettboom.

* Fortran wrappers

  - Wrapper for wcsbchk().

* PGSBOX

  - Fixed a few nuisance warnings from gfortran 4.7.2 relating to
    implicit type conversions in pgsbox.f.

* User manual

  - Added mention of wcsjs (Javascript) in the section on other
    packages.


WCSLIB version 4.19 (2013/09/30)
--------------------------------

* C library

  - Bug fix in wcshdo(), uncovered by cppcheck and reported by David
    Binderman.  Fixed additional minor inconsistencies in hpxx2s(),
    wcsprintf(), and wcsfprintf() reported by cppcheck.

  - Minor fix to twcstab reported by cppcheck.

  - Bug fix in wcssub() for handling (non-standard) PROJPn keywords
    (uncovered by valgrind, reported by Paul Price).


WCSLIB version 4.18 (2013/07/13)
--------------------------------

* C library

  - Implemented the butterfly projection (XPH), being the polar form of
    the HEALPix projection with (H,K) = (4,3).  Augmented tprj1.c and
    tprj2.c to suit.

  - Bug fix in celfix() when translating GLS to SFL with non-zero
    reference point.

* Fortran wrappers

  - Wrappers for the XPH projection functions and corresponding
    modifications to the test programs.

  - Fixed a few inconsequential warnings from gfortran 4.7.2 relating
    to implicit type conversions in the test programs.

* Utilities

  - In HPXcvt, fixed incorrect axis scaling (CDELT1 and CDELT2) in the
    XPH header, and set the PCi_ja matrix in the HPX header to a pure
    45 degree rotation with appropriate adjustment of CDELT1 and CDELT2
    (matching XPH).  Also set LONPOLE to 180 degree in the XPH header
    with adjustment of CRVAL1 as recommended in the errata.  These
    changes prompted by Paddy Leahy.  Also, modified the FITS header
    comment for XPH - it is no longer "experimental", and accept the
    '-x' option (i.e. without qualification) as equivalent to '-xn'.

* User manual

  - Documentation generation moved to doxygen 1.8.4 (was 1.5.6).


WCSLIB version 4.17 (2013/01/29)
--------------------------------

* C library

  - Added wcsfprintf() to wcsprint.h.  Now used in wcsbth() and wcspih()
    to allow diagnostic output to be redirected.  Changes provided by
    Michael Droettboom.


WCSLIB version 4.16 (2012/11/07)
--------------------------------

* C library

  - When wcspih() constructs a default coordinate representation it will
    give it the special name "DEFAULTS", and will not report "Found one
    coordinate representation" (if reporting is enabled).

* Utilities

  - wcsware has a new option, -P, which does the same as -p except that
    it won't print a wcsprm struct with the name "DEFAULTS".


WCSLIB version 4.15 (2012/09/26)
--------------------------------

* C library

  - Bug fixes in spctype(), spcspxe(), spcxpse, and spctrne() for
    propagating an error status correctly from lower-level routines.
    Amendments to the prologues of these routines.  Reported by
    Hans Terlouw.

  - Similarly for wcsunitse(), wcsulexe(), and wcsutrne().

* PGSBOX

  - Bug fix in PGSBOX for handling cycles in angle when both world
    coordinate elements are angular.  Reported by Thomas Robitaille.


WCSLIB version 4.14 (2012/07/13)
--------------------------------

* C library

  - Problems were caused for fitshdr(), wcsbth(), wcspih(), wcsulex(),
    datfix() and wcshdo(), by locales such as "fr_FR" in which commas
    are used to delimit the decimal part of floating point numbers.
    In particular, these locales adversely affect the behaviour of
    sscanf() and sprintf() when reading and writing FITS header
    keyvalues.  Thread-safe fixes provided by Michael Droettboom.

  - Applied astropy patches from Michael Droettboom: attend to compiler
    warnings in prj.c, spc.c, tab.c, and wcsutil.c, including those for
    MS-Windows.


WCSLIB version 4.13.4 (2012/04/02)
----------------------------------

* Installation

  - Relaxed the closure tolerance slightly in tlog.f as for tlog.c
    previously.


WCSLIB version 4.13.3 (2012/03/26)
----------------------------------

* Installation

  - Relaxed the closure tolerance slightly in tlog.c for gcc 4.6.3 on
    Ubuntu 12.04 (reported by Ole Streicher).


WCSLIB version 4.13.2 (2012/03/21)
----------------------------------

* Installation

  - Changes to configure.ac and the GNUmakefiles to put '-lm' strictly
    in the correct sequence when producing the sharable library
    (reported by Ole Streicher).


WCSLIB version 4.13.1 (2012/03/15)
----------------------------------

* C library

  - Workaround in wcserr_set() for an unfortunate compiler segv from
    gcc 4.2.1 in MacOSX 10.7.


WCSLIB version 4.13 (2012/03/14)
--------------------------------

* C library

  - Allow naxis == 0 in wcsini() and linini() for a degenerate
    coordinate system as may be produced by wcssub().  In wcssub(),
    ensure that wcsini() is called for coordinate systems with
    naxis == 0.  In wcssptr(), call spcfree() before spcini() to plug a
    memory leak.


WCSLIB version 4.12 (2012/02/29)
--------------------------------

* C library

  - In spctrne(), guard against restfrq == restwav == 0.0 when
    translating between two velocity-characteristic types, or between
    two wave-characteristic types (the translation is independent of
    restfrq and restwav, but a dummy value is needed for intermediate
    calculations).


WCSLIB version 4.11 (2012/02/21)
--------------------------------

* C library

  - Bug fix in spcset() for handling simple linear spectral axes.

* Fortran wrappers

  - Bug fix in spctrne_() for handling ctypeS2.


WCSLIB version 4.10 (2012/02/06)
--------------------------------

* C library

  - datfix() and spcfix() now return informative messages when dates and
    AIPS-convention spectral axes are translated (changes contributed by
    Michael Droettboom).  spcaips() now returns an error status for
    invalid values of VELREF.

  - wcssub() has been augmented with the ability to add new axes onto a
    wcsprm struct.


WCSLIB version 4.9 (2012/01/24)
-------------------------------

* C library

  - Fixes to wcsfixi() for collecting the messages properly in the info
    array (from Michael Droettboom).

  - Handle certain malformed date strings more gracefully in datfix().

  - Make informative messages printed by wcserr_prt() a bit more
    informative.


WCSLIB version 4.8.4 (2011/12/05)
---------------------------------

* C library

  - Fixed the pseudo-random number generator in twcstab.c - gcc 4.6 with
    '-O2' baulked at testing for signed integer overflow.

* Installation

  - In configure.ac, the Fortran compiler's libraries must be added to
    the link list when checking for the PGPLOT libraries since gcc is
    driving the linker.  Likewise in C/GNUmakefile when linking test
    programs that use PGPLOT.

  - Use 'make CHECK=nopgplot check' to run only the non-graphical tests
    (even if PGPLOT is available).

  - After compiling and running the tests, 'make check' now summarizes
    the non-graphical test results and stops if any failed.


WCSLIB version 4.8.3 (2011/11/17)
---------------------------------

* C library

  - Minor generalization of the wcserr diagnostics to allow the return
    of informative messages, which are associated with negative status
    values.  wcserr_prt() will now recognize and print them as such.
    Added wcserr_clear() to reset (clear) a wcserr struct.

  - Modified unitfix() to return an informative message if a units
    alias is applied, and wcsfixi() to allow such messages to be
    propagated through the info array (from Michael Droettboom).

  - Modified twcsfix.c to use wcserr diagnostics, in particular to
    report units alias translations.

* Fortran wrappers

  - In wcsfix_(), interpret *naxis == 0 as meaning naxis == 0x0, thus
    causing cylfix() to be skipped.

  - Modified twcsfix.f to reflect changes made to twcsfix.c.


WCSLIB version 4.8.2 (2011/10/04)
---------------------------------

* Installation

  - Changes for Debian package generation contributed by Ole Streicher:
    - Corrections to 'configure' reported by 'lintian'.
    - Generate man pages for the utility programs and install them.


WCSLIB version 4.8.1 (2011/09/19)
---------------------------------

* Installation

  - Set SONAME in the sharable library in accordance with
    tldp.org/HOWTO/Program-Library-HOWTO/shared-libraries.html
    (reported by Ole Streicher, Debian package maintainer).  The
    sharable library will again be installed with full release number
    and with a symbolic link from SONAME pointing to it.  If defined,
    SHRLN will point to SONAME.


WCSLIB version 4.8 (2011/08/15)
-------------------------------

* C library

  - New error diagnostics mechanism contributed by Michael Droettboom:

    Most functions that return a numeric status (error) code now also
    write a detailed error message to a wcserr struct attached to the
    passed-in *prm struct.  See wcserr.h for more information.

    Functions that didn't have a *prm struct as an argument have no
    direct way to return an error message.  Therefore, these functions
    now have duplicate versions with the suffix "e" that take an
    additional "struct wcserr *" parameter.  These functions are:

        spcspx()    ->  spcspxe()
        spctrn()    ->  spctrne()
        spctyp()    ->  spctype()
        spcxps()    ->  spcxpse()
        wcsulex()   ->  wcsulexe()
        wcsunits()  ->  wcsunitse()
        wcsutrn()   ->  wcsutrne()

    A new function wcsfixi() was added which is identical to wcsfix()
    but in addition stores all of the detailed textual messages about
    the fixes that were performed.

  - In wcssub(), ensure that wcstab->m_tab has been initialized
    before trying to free it on status return 12 or 13 (reported by
    Hans Terlow).

  - Bug fixes:
    - In sphx2s() and sphs2x() for the case where |eul[1]| = 180.0.
    - For parsing AIPS-convention VELREF in wcsbth().
    - In spcaips() for translating AIPS-convention CTYPEia without
      Doppler frame.

  - Non-graphical test programs now simply report "PASS" if they satisfy
    the reporting tolerance for closure residuals, etc.  Their full
    output is reported otherwise.  Run 'make MODE=interactive check' to
    revert to the previous behaviour of reporting the full output for
    tests that succeed.

  - Eliminated compiler warnings about type-punning of pointer-to-
    function.

* Fortran wrappers

    Extensive modifications to track the new error handling mechanism
    in the C library.

* Installation

  - configure now prefers gfortran over g77 if available.

  - Don't rely on "." being in the PATH if config.status needs to be
    run in the pgsbox and utils makefile (reported by Peter Teuben).


WCSLIB version 4.7 (2011/02/07)
-------------------------------

* C library

  - Bug fix in celset() for interpreting LATPOLEa when LONPOLEa = phi0.
    Crept in at version 4.4.

  - Fixed the bounds test on y in hpxx2s() (HEALPix projection) for
    unconventional values of H and K.  In hpxx2s() and hpxs2x(),
    corrected the offset of the southern polar half-facets for
    even K.  In hpxs2x(), put the phi = 180 meridian in the expected
    place.

  - Bug fixes in tabx2s() and tabs2x() for default indexes (reported
    by David Berry).  In tabs2x(), if no solution is found then do
    minor extrapolation past the ends of each row (1-D case only).
    Sped up tabs2x() by about 50%.

  - New functions wcsprintf(), wcsprintf_set(), and wcsprintf_buf(),
    declared in wcsprintf.h, provide control over the disposition of
    output from celprt(), linprt(), prjprt(), spcprt(), tabprt(), and
    wcsprt() routines.  Prompted by Michael Droettboom, with an initial
    implementation.

* Fortran wrappers

  - In the various test programs, used EQUIVALENCEs to ensure that the
    CEL, LIN, PRJ, etc. arrays are aligned on a DOUBLE PRECISION
    boundary.

* PGSBOX

  - Bug fix for the case where NG1 == 0 and GRID1(0) < 0, and likewise
    for NG2 and GRID2.

* Utilities

  - In wcsware, added a '-w' option to convert world coordinates
    obtained from stdin to pixel coordinates using wcss2p().  Allow
    multiple sets of input coordinates with the '-x' and '-w' options
    and report the value of the intermediate world coordinates.

* User manual

  - Fixed list formatting for function return values < 0 or > 9.

  - New section for wcsprintf() and related routines.

* Installation

  - Changes prompted by Sbastien Fabbro for the Gentoo Linux package:
      a) autoconf updates,
      b) respect LDFLAGS when building the shared library,
      c) install documentation,
      d) recognise DESTDIR for doing a staged installation.

  - As of this release, the minor WCSLIB version number (second field)
    will be incremented if and only if a change is made that affects the
    library itself, not the documentation or utilities.  The version
    number on the installed libraries and header files will omit the
    patch number (third field).


WCSLIB version 4.6.3 (2010/11/24)
---------------------------------

* C library

  - Bug fix in wcsbth() for handling the inheritance of image header
    keywords (uncovered by valgrind, reported by Jim Lewis).


WCSLIB version 4.6.2 (2010/11/22)
---------------------------------

* C library

  - Fixed a memory leak in wcsbth.l (reported by Jim Lewis).


WCSLIB version 4.6.1 (2010/11/18)
---------------------------------

* Fortran wrappers

  - Fixed typos in cel_f.c, celget[cdi] -> celgt[cdi].


WCSLIB version 4.6 (2010/11/16)
-------------------------------

* C library

  - In wcsulex.l and wcsutrn.l, stdlib.h must be included explicitly
    before the redefinition of exit() - most versions of flex do include
    it upfront but some don't (reported by Peter Williams).

* Fortran wrappers

  - Changes intended to avert nuisance compiler warnings that could
    potentially obscure warnings indicative of a genuine problem:

    - To stop messages about unused variables when the relevant compiler
      option is set, e.g. 'g77 -Wunused', the various *_ERRMSG arrays
      defined in the Fortran include files and (formerly) initialized
      therein via DATA statements, e.g. PRJ_ERRMSG in prj.inc, have now
      been placed into COMMON blocks with names such as PRJ_DATA, and
      are initialized via DATA statements in BLOCK DATA subprograms
      defined in separate files, e.g. prj_data.f.

    - To stop messages about subroutines being invoked with inconsistent
      argument lists if the relevant compiler option is not set, e.g.
      'g77 -Wno-globals', the C wrapper functions that take 'void *'
      arguments now have separate forms for INTEGER, DOUBLE PRECISION,
      and CHARACTER arguments that simply invoke the generic function.
      Application code must be modified to take advantage of this.

* User manual

  - In the section on the Fortran wrappers in the manual, warn about the
    need for the INTEGER array holding a data structure to be aligned on
    a DOUBLE PRECISION boundary.


WCSLIB version 4.5.6 (2010/10/28)
---------------------------------

* Installation

  - Fixed the search for CFITSIO and PGPLOT library and include
    directories.


WCSLIB version 4.5.5 (2010/10/14)
---------------------------------

* Installation

  - Build the PGSBOX sharable library.


WCSLIB version 4.5.4 (2010/09/28)
---------------------------------

* C library

  - In wcshdo(), according to the FITS standard, "Letters in the
    exponential form ('E' or 'D') shall be upper case" (reported by
    Michael Droettboom).


WCSLIB version 4.5.3 (2010/09/23)
---------------------------------

* Utilities

  - Various improvements to wcsgrid: correct the scaling set via
    cpgwnad(); label angles other than RA,Dec in decimal degrees;
    draw the projection boundary for projections other than zenithals.


WCSLIB version 4.5.2 (2010/09/23)
---------------------------------

* C library

  - Fixed the translation of GLS to SFL in wcsset() and celfix() when
    the reference longitude is non-zero - it introduces an offset in
    longitude in the normal way.  (This undoes part of the change
    applied in version 4.4.)


WCSLIB version 4.5.1 (2010/08/12)
---------------------------------

* C library

  - New utility function, sphpad(), computes the coordinates of points
    offset by given angular distances and position angles from a given
    point on the sky (complementary to sphdpa()).

* Fortran wrappers

  - New wrapper function:
    - SPHPAD for sphpad().


WCSLIB version 4.5 (2010/07/16)
-------------------------------

* C library

  - Fixed the interpretation of VELREF when translating AIPS-convention
    spectral types.  Such translation is now handled by a new special-
    purpose function, spcaips().  The wcsprm struct has been augmented
    with an entry for velref which is filled by wcspih() and wcsbth().
    Previously, selection by VELREF of the radio or optical velocity
    convention for type VELO was not properly handled.

* Fortran wrappers

  - New wrapper function:
    - SPCAIPS for spcaips().

  - Changed spc.inc, spc_f.c, wcs.inc and wcs_f.c to track VELREF
    changes.

  - Declared functions external in the include files to avoid compiler
    warnings about unused variables (if the particular option is set).

* Utilities

  - Added a '-q' option to fitshdr to quit after a specified number
    of HDUs.


WCSLIB version 4.4.4 (2009/09/14)
---------------------------------

* Installation

  - Added more configure options for controlling the build:
    --disable-fortran, --disable-utils, --without-cfitsio, and
    --without-pgplot.


WCSLIB version 4.4.3 (2009/09/03)
---------------------------------

* C library

  - Set wave number units to "/m" in spctyp(), was "1/m" which is not
    strictly legal and wasn't handled by wcsulex() (reported by
    Hans Terlow).  Also fixed a number of units specifications in the
    prologue of spx.h to conform with Paper I usage.

  - In wcsulex(), allow unit strings like "1/m" in addition to "/m",
    provided that the superfluous "1" is the first non-blank character
    in the expression, or parenthesised sub-expression.

  - In wcssptr(), ensure that i is always reset if given < 0.

* User manual

  - Augmented the list of FITS WCS and related software in the manual.


WCSLIB version 4.4.2 (2009/08/13)
---------------------------------

* C library

  - In sphx2s() and sphs2x(), handle the case where |eul[1]| = 180.0
    separately for speed and accuracy.  This change also fixes a rare
    and subtle bug in cels2x() that occurs when celprm::isolat is set
    and the magnitude of the first latitude in the lat[] vector exceeds
    90 deg (reported by Hans Terlouw).

* Installation

  - Fix relating to creation of symlinks when installing the libraries.


WCSLIB version 4.4.1 (2009/08/11)
---------------------------------

* Installation

  - Fixes for installation of the CHANGES file and for the creation of a
    symbolic link for the sharable library if one already exists.


WCSLIB version 4.4 (2009/08/10)
-------------------------------

* C library

  - Creation of WCSLIB user manual from the header file prologues using
    a special-purpose parser, doxextr, and sed scripts to generate input
    for doxygen.  This required minor formatting changes to all
    prologues plus miscellaneous changes such as naming of arguments in
    function prototypes.

  - Bug fix in wcsset() that affected handling of PROJPn (deprecated)
    and PVi_ma attached to the longitude (not latitude) axis.  Guard
    against long strings when copying the projection code.  In
    wcs_types(), allow for early Paper IV distortion codes (e.g.
    "RA---TAN-SIP") when parsing CTYPEia.

  - Use sincos() whereever possible for a ~15% speedup (patches for
    cel.c, prj.c and sph.c supplied by Michael Droettboom).  configure
    checks for, and uses it automatically if available.

  - Fixed the translation of GLS to SFL in wcsset() and celfix() when
    the reference longitude and latitude are non-zero.  (In the AIPS
    convention, this simply translates the reference point, i.e. the map
    as a whole, to those coordinates without creating an oblique grid.)

  - Bug fix in prjoff(), a utility function used by the prj routines.
    It forces (x,y) = (0,0) at (phi_0,theta_0) when the latter are set
    by PVi_[012]a attached to the longitude (not latitude) axis.  Rarely
    used in practice.

  - New utility function, sphdpa(), computes the distance and position
    angle from a point on the sphere to a set of field points.

  - In sphx2s() and sphx2s(), handle a simple change in origin of
    longitude using a short-cut calculation for speed and accuracy.
    Similarly in celset(), check whether phip == phi0 when computing
    latp and if so use a short-cut that ensures latp == 90.0 (exactly)
    if lat0 == theta0.  The resulting spherical rotation then becomes a
    simple change in origin of longitude.  In particular, these changes
    should assist PGSBOX in drawing grid lines of +/-180 longitude, to
    prevent flip-flopping between one and the other.

  - wcsbth() & wcspih(): resolved an inconsistency between the
    documentation and code by renamimg WCSHDR_VSOURCEa as
    WCSHDR_VSOURCE.

  - Flex code: moved declaration of helper functions out of global
    scope.

  - Fixed the call to wcss2p() in twcshdr (in a section of code not
    usually exercised).

* Fortran wrappers

  - New wrapper functions:
    - WCSBTH for wcsbth(),
    - WCSBDX for wcsbdx(),
    - CDFIX  for cdfix(),
    - SPHDPA for sphdpa().

  - Updated WCSLEN (in wcs.inc) and added WCS_COLAX and WCS_VELANGL to
    match changes to wcsprm made in v4.3 with corresponding changes to
    the wrapper functions.  Likewise updated TABLEN (in tab.inc) for
    changes to tabprm, and added CEL_LATPREQ for celprm.

  - Struct lengths (WCSLEN, PRJLEN, etc.) are now long enough to
    accomodate 64-bit machines.

  - Updated the flag bits for the RELAX argument in wcshdr.inc to
    reflect changes to wcshdr.h made in v4.3.  Renamed WCSHDR_VSOURCEa
    to WCSHDR_VSOURCE for consistency with the C library.

* PGSBOX

  - Improved grid labelling, particularly in minimizing the number of
    fields required in sexagesimal labels.

* Utilities

  - New utility program:

    - wcsware extracts the WCS keywords for an image from the specified
      FITS file, constructs wcsprm structs for each coordinate
      representation found, and performs a variety of operations using
      them.

  - Old utility programs (first appeared in 4.3 but were not recorded):

    - HPXcvt reorganises HEALPix data into a 2-D FITS image with HPX
      coordinate system.

    - wcsgrid extracts the WCS keywords for an image from the specified
      FITS file and uses pgsbox() to plot a 2-D coordinate graticule for
      each alternate representation found.

    - fitshdr lists headers from a FITS file specified on the command
      line, or else on stdin, printing them as 80-character keyrecords
      without trailing blanks.

* Installation

  - New configure options, --with-pgplotinc, --with-pgplotlib,
    --with-cfitsioinc and --with-cfitsiolib allow additional directories
    to be added to the library and include file search path.

  - Miscellaneous fixes and improvements to the installation process.

  - Generate a metadata file for pkg-config.

  - Added 'make MODE=interactive check' to run the test programs in
    interactive mode rather than batch.

  - Merged the separate CHANGES files for C, Fortran and PGSBOX into
    one (this), with a new section for utilities.


WCSLIB version 4.3.3 (2009/04/30)
---------------------------------

* C library

  - fitshdr.l, wcsbth.l, and wcspih.l: use setjmp/longjmp to preempt
    the call to exit() which is hard-coded in function yy_fatal_error()
    supplied by flex.

  - wcspih.l: if NAXIS is non-zero but there were no WCS keywords at
    all in the header then create a default WCS with blank alternate
    version.


WCSLIB version 4.3.2 (2009/03/16)
---------------------------------

* C library

  - utils/GNUmakefile: create BINDIR if necessary prior to installing
    utilities.


WCSLIB version 4.3.1 (2008/09/08)
---------------------------------

* Installation

  - Top-level GNUmakefile: install header files.


WCSLIB version 4.3 (2007/12/27)
-------------------------------

* C library

  - A new general WCS header parser wcsbth() handles binary table image
    arrays and pixel lists as well as image array headers.  Added
    "colax" to the wcsprm struct to record the column numbers for each
    axis in a pixel list.

  - New function wcsbdx() is the analog of wcsidx() for the array of
    wcsprm structs returned by wcsbth().

  - New function wcshdo() writes out a wcsprm struct as a FITS header.

  - Changes to wcspih():
    - Bug fix, check for a == 0 (indication of a keyword that applies
      to all alternates) in internal helper function wcspih_naxes()
      (reported by Craig Markwardt).
    - Added a new ctrl option to remove valid WCS keyrecords except for
      those with a more general role, namely {DATE,MJD}-{OBS,AVG} and
      OBSGEO-{X,Y,Z} (suggested by Jim Lewis).
    - Added a rule for VELANGLa.  Also added "velangl" to the wcsprm
      struct.
    - Do checks on the i, k & m keyword parameters in <VALUE>.
    - Fixed the test for repeated blanks in the NAXIS and WCSAXES
      patterns.
    - Fixed three <CCi_ma> rules to allow m == 0.
    - Reworked the implementation notes in the prologue.

  - The flex scanners, fitshdr.l, wcsbth.l, wcspih.l, wcsulex.l, and
    wcsutrn.l, invoke yylex_destroy() before returning to avoid a 16kiB
    memory leak.  This was reported by several people, however it may be
    problematic depending on the version of flex used - version 2.5.9 or
    later is required.  If this is not available, C sources pre-
    generated by flex 2.5.33 will be used.

  - In wcs.c, don't define the signbit macro if already defined (for
    MacOSX).

  - In wcs.h, documented wtbarr namespace issues in C++.

  - In wcsset(), always set wcsprm.cunit[i], if possible (primarily for
    use by wcshdo()).

  - In wcsfix.c, parenthesised a boolean expression that was otherwise
    incorrect.

  - Fixed an obscure floating point rounding error in celset() that
    appeared with -O2 optimization in gcc v3.3.5 (Linux).

  - prjset() now correctly propagates the status value returned by the
    specific projection-setting functions (reported by Bill Pence).

  - Bug fix in hpxx2s(), also added bounds checking.  Minor efficiencies
    in carx2s() and merx2s().

  - In the various functions that print the contents of the structs, use
    the "%p" printf conversion specifier to print addresses rather than
    casting the pointer to int and using "#x".  The latter does not work
    on 64-bit machines where sizeof(int) != sizeof(void*).

  - Reorganized the various structs to get alignment on 64-bit machines.

  - All header file prologues now reference the README file for an
    overview of the library.

  - Miscellaneous portability fixes for 64-bit, MacOSX, OSF compiler,
    etc.

  - Elimination of compiler warnings, e.g. parenthesised assignments
    used as truth values (a favourite gcc gripe!), etc.

  - Process flex descriptions using a newer version of flex, primarily
    for MacOSX.  However, the processed files are now only used when
    flex 2.5.9 or later is not available.

  - Removed WCSLIB 2.x backwards-compatibility measures from lin.h,
    prj.h, prj.c, and sph.h.

* Fortran wrappers

  - (No substantive changes.)

* PGSBOX

  - Miscellaneous improvements to PGSBOX.

* General

  - Switched licensing to LGPL 3.0.

  - In comment text, replaced use of the obsolete term "card" with
    "keyrecord" which consists of a "keyword", "keyvalue", and
    "keycomment".

* Installation

  - General improvements to the installation process: autoconf-related
    portability improvements, particularly relating to Fortran name
    mangling; makefile rules for building the shared library, for
    processing flex descriptions; don't rely on "." being in the PATH
    when running tests.


WCSLIB version 4.2 (2005/09/23)
-------------------------------

* C library

  - Brought the installation process under control of GNU autoconf,
    the top-level makefile now builds and tests everything, and the C
    library has a config.h in which WCS_INT64 is set.  Added an INSTALL
    file.

  - Merged the FORTRAN, C and PGSBOX READMEs into one top-level README.

  - Extensions for -TAB coordinate handling: in tabx2s() and tabs2x(),
    allow extrapolation by half a cell at either end of the index and
    coordinate tables; fits_read_wcstab() (in getwcstab.{h,c}) allows
    TDIMn to be omitted for 1-D lookup tables for which it has the form
    '(1,K)', i.e. describing a degenerate 2-D array; wcsprt() now prints
    the wtbarr structs in wcsprm.

  - Bug fixes for -TAB coordinate handling: in tabx2s() and tabs2x()
    the incorrect indexing variable, m instead of i, was used for
    tab->crval[]; wcsp2s() and wcss2p() returned prematurely in the
    tabular coordinate loop; in wcstab(), removed an extraneous
    assignment to wtbp->kind for index arrays.

  - In wcsp2s() and wcss2p(), elements of the stat[] vector that had
    been set were being reset incorrectly to zero.  The stat[] values
    are now set as flag bits for each coordinate element.

  - Added cdfix() to the wcsfix() suite to fix erroneously omitted
    CDi_ja cards.

  - PGSBOX is now compiled into a separate object library, and is
    installed alongside WCSLIB.

  - Eliminated several instances of non-ANSI C library functions and
    header files and some residual K&R C usage.  The Sun C compiler
    complained about const int definitions of initializers used in
    variable declarations in some of the test programs; changed these
    to preprocessor macros.

* Fortran wrappers

  - Fixed handling of 64-bit integer keyvalues in keyget_().

  - Fixed output formatting of 64-bit integer keyvalues in tfitshdr.f.

  - Fixed minor syntax errors in twcsfix.f and tpih1.f reported by the
    Sun Fortran compiler.

  - The output of each test program now identifies the source file.

* PGSBOX

  - (No substantive changes.)


WCSLIB version 4.1 (2005/08/31)
-------------------------------

* C library

  Summary of added functionality:

  - -TAB coordinate axes are now fully implemented in the WCSLIB driver
    functions (in wcs.{h,c}); multiple -TAB axes are supported.  A new
    function, wcstab(), which is automatically invoked by wcspih(),
    parses -TAB-related header cards and sets up structs for a separate
    routine that reads the necessary arrays from a FITS binary table
    extension.

    An implementation of this routine in CFITSIO, fits_read_wcstab(),
    is provided.  Note however that the interface of this function is
    experimental, and the code itself must be considered beta-release in
    WCSLIB 4.1.

  - Units specifications, either from CNAMEia or inline comments (with
    brackets), of arbitrary complexity are now fully implemented via a
    parser, wcsulex(), and converter, wcsunits().  This is invoked
    automatically by wcsset().

  - Translators for non-standard WCS constructs are provided.  These
    cover date formats, units specifications, defunct celestial
    projection types, AIPS spectral axis types, and the repair of
    malformed cylindrical coordinate systems.

  - wcspih() now has options to remove the WCS cards it has processed
    from the header and a new generic FITS header parser, fitshdr(), may
    be used to parse the remaining non-WCS cards.  In addition to the
    more basic types, it handles 64-bit and 'very long' (70 digit)
    integer keyvalues, and also continued string keyvalues.  It also
    does keyword matching and extracts units specifications in inline
    comments.

  - -LOG coordinates are now implemented independently of spectral
    coordinate types.  Multiple -LOG axes are supported.

  - New function wcssptr() translates the spectral axis in a wcsprm
    struct to the required type.

  - The README file now gives an introduction to, and complete overview
    of, WCSLIB.  It provides a point of entry to programming with
    WCSLIB.  Complete descriptions and usage notes for all functions are
    contained in the header files.

  - The FORTRAN wrappers and test programs are now completely up-to-date
    with respect to the C implementation.

  - All code, including the FORTRAN wrappers, PGSBOX, and all test
    programs, now pass 'purify' without memory leaks, uninitialized
    memory reads, memory access violations, or other memory faults.

  Change notes:

  - Added options to wcspih() to remove WCS cards from the input header
    leaving only non-WCS cards behind.  Modified test programs tpih1.c
    and tpih2.c to use CFITSIO optionally via preprocessor macro
    DO_CFITSIO.

  - New function wcstab() in wcshdr.{h,c} parses -TAB-related header
    cards and sets up structs for a separate routine that reads the
    necessary arrays from a FITS binary table extension.  New
    test/demo program twcstab.c using header defined in wcstab.cards.

  - CFITSIO implementation, fits_read_wcstab() in getwcstab.{h,c}, of a
    function, independent of WCSLIB, for extracting arrays from a binary
    table as required in constructing -TAB coordinates.

  - New units specification parser, wcsulex() in wcsunits.h and
    wcsulex.l, and converter, wcsunits() in wcsunits.{h,c}.  New
    test/demo program tunits.c.

  - New parser for non-standard units specifications, wcsutrn() in
    wcsunits.h and wcsutrn.l, also tested by tunits.c.

  - New functions datfix(), unitfix() (which applies wcsutrn()),
    celfix(), and spcfix() join cylfix() in wcsfix.{h,c} to translate
    various forms of non-standard or quasi-standard FITS WCS keyvalues
    in a wcsprm struct.  wcsfix() applies all of these in sequence.
    New test/demo program twcsfix.c, with wcsfix() also now invoked by
    tpih1.c.

  - New generic FITS header parser, fitshdr() in fitshdr.{h,l}.  New
    test/demo program tfitshdr.c uses wcs.cards with extra non-WCS
    cards added.

  - -LOG coordinates are now treated as a coordinate type separate from
    spectral coordinates, implemented via log.{h,c} and test program
    tlog.c.  The logarithmic functions were removed from spx.{h,c}, and
    spc.c.

  - Extensive changes to wcs.{h,c} to support multiple -TAB and -LOG
    coordinate axes and units conversion.  Substantially changed the
    test program, twcs.c, to test the more general functionality.

  - New function wcssptr() in wcs.{h,c} translates the spectral axis in
    a wcsprm struct.

  - Added DATE-AVG to wcsprm.  Also ntab, tab, nwtb, and wtb required
    for -TAB implementation.  Define struct wtbarr.

  - Added a types[] member to the wcsprm struct to identify axis
    coordinate types using a four-digit code.

  - Use memset() in wcsini() to null-fill character arrays in the wcsprm
    struct so that they don't appear to be padded with garbage when
    displayed by gdb.

  - Do alias translation for AIPS-convention spectral types in wcsset()
    using spctyp().  If wcsset() finds a CTYPEia in "4-3" form with an
    unrecognized algorithm code it now returns an error rather than
    assume that it's a linear axis.  wcsset() now also resets lonpole
    and latpole to the values actually used.

  - Modified spctyp() to translate AIPS-convention spectral ctypes, and
    modified the argument list to return the parsed spectral type and
    algorithm code.  The return arguments will not be modified if
    CTYPEia is not a valid spectral type; zero-pointers may be specified
    for any that are not of interest.  Removed the external const
    variables, spc_codes and spc_ncode, as their function is now
    fulfilled by spctyp().

  - Fixed a bug in spctrn() in resolving ctypeS2 wildcarding.

  - Added latpreq member to the celprm struct, set by celset() to
    indicate how LATPOLE is used.  Augmented tcel2.c to report it.

  - New function tabmem() in tab.{h,c} takes control of user-allocated
    memory.

  - tabini() allows K == 0 and also K[m] == 0 to initialize partially
    the tabprm struct (for wcstab()).  It now does fine-grained
    bookkeeping of memory allocation for the index arrays and allocates
    each individually.  tabprm.index[] == 0x0 is recognized as default
    indexing in tabset(), tabx2s() and tabs2x().

  - The *prt() functions report parameters to an extra decimal place.

  - tabprt() prints the array index for elements of the coordinate and
    index vectors.

  - Set the 0th element in all *_errmsg arrays to "Success".

  - Extracted string utility functions used by WCSLIB into
    wcsutil.{h,c}.

  - Removed support for K&R C.

* Fortran wrappers

  - The FORTRAN wrappers and test programs are now completely up-to-date
    with respect to the C implementation.

  - New include files, wrappers, and test programs:
    fitshdr.inc, fitshdr_f.c, getwcstab.inc, getwcstab_f.c, log.inc,
    log_f.c, sph.inc, tab.inc, tab_f.c, tfitshdr.f, tlog.f, ttab1.f,
    ttab2.f, ttab3.f, tunits.f, twcsfix.f, twcstab.f, wcsfix.inc,
    wcsfix_f.c, wcsunits.inc, wcsunits_f.c.

  - Updates to reflect changes to the C library and test programs:
    cel.inc, cel_f.c, prj.inc, spc.inc, spc_f.c, spx.inc, spx_f.c,
    tlin.f, tpih1.f, tpih2.f, tprj1.f, tprj2.f, tspc.f, tsph.f, tspx.f,
    twcs.f, twcsmix.f, twcssub.f, wcs.inc, wcs_f.c, wcshdr.inc,
    wcshdr_f.c.

  - Added *_ERRMSG arrays containing status messages to all include
    files.

  - Removed support for K&R C.

* PGSBOX

  - Fixed a subtle though benign memory fault identified by 'purify'.

  - Reset LATPOLE in the COE example in cpgtest.f when drawing the
    second (native) grid because it will have been set to a non-default
    value by wcsset() when the first grid was drawn; set wcs.flag to -1
    before wcsinit() and call wcsfree() at the end.  Similarly for
    pgtest.f.


WCSLIB version 4.0 (2005/02/07)
-------------------------------

* C library

  - Implemented tabular coordinates (-TAB).  New files: tab.h and tab.c,
    and test programs ttab[123].c.  These have not been incorporated
    into the higher-level (wcs.h) functions at this stage.

  - New spectral functions: spchek() checks a spectral algorithm code
    for legitimacy; from the spectral keywords given, spcspx() derives
    the corresponding CRVALi and CDELTi keywords for the underlying P-,
    and X-type spectral coordinates; spcxps() does the opposite;
    spctrn() combines spcspx() and spcxps() to translate one set of
    spectral keywords into another, e.g.  'FREQ' -> 'ZOPT-F2W'.

  - Implemented the HEALPix (HPX) projection in the prj functions.

  - Added a new function, wcsidx(), to return an array that indexes the
    alternate coordinate descriptions found by wcspih() (suggested by
    Bill Pence, NASA/Goddard).  Modified tpih1.c to exercise it.

  - In wcsp2s() and wcss2p(), check that nelem equals or exceeds
    wcs.naxis; emphasised this in the usage notes for these functions
    in tab.h (suggested by Bill Pence, NASA/Goddard).

  - Moved the macros used for UNDEFINED values and the corresponding
    macro test function, undefined(), to wcsmath.h for general use.
    Previously, UNDEFINED values were only used internally, but they are
    now visible in some of the structs, particularly values of undefined
    auxiliary header cards in the wcsprm struct.

  - Remove const from the double args in the specx() prototype in spx.h
    to match the definition in spx.c (reported by Bryan Irby,
    NASA/Goddard).

  - Fixed the interaction between the FLAVOUR and PGPLOTLIB definitions
    in the C and FORTRAN Makefiles by introducing a separate variable,
    DO_PLOTS, to control whether to exercise test programs that require
    PGPLOT (reported by Bill Pence, NASA/Goddard).

* Fortran wrappers

  - New wrapper defined in wcshdr_f.c: wcsidx_().  Modified test program
    tpih1.f to use it.

* PGSBOX

  - (No substantive changes.)

* General

  - Changed the copyright notice in all library routines from LGPL to
    GPL as recommended by the FSF (http://www.gnu.org/licenses/why-not-
    lgpl.html).

* Installation

  - General improvements to the installation process: fixed the
    interaction between the FLAVOUR and PGPLOTLIB definitions in the
    Makefile by introducing a separate variable, DO_PLOTS, to control
    whether to exercise test programs that require PGPLOT (reported by
    Bill Pence, NASA/Goddard).  Added an "install" target to the
    Makefile.


WCSLIB version 3.6 (2004/08/25)
-------------------------------

* C library

  - New service routine, wcssub() extracts the coordinate description
    for a subimage from a wcsprm struct.  wcscopy() is now implemented
    as a preprocessor macro that invokes wcssub().  New test program,
    twcssub.c, tests wcssub().

  - In wcspih():

    1) Fixed handling of string-valued keywords where the inline comment
       contains a single-quote character (').

    2) Fixed the address arithmetic for EPOCH and VELREF.

    3) Translate VSOURCEa into ZSOURCEa if required.

    4) Recognize SSYSSRCa.

    5) Support free-format string keyvalues, as well as integer and
       floating-point keyvalues; documented this in the prologue of
       wcshdr.h.

    6) Allow header cards without inline comments.

    7) Fixed function prototyping in wcspih.l (i.e. ANSI and non-ANSI
       forms were potentially mixed).

    8) Catch an unhandled newline character on the END card that was
       echoed to stdout.

    9) In error messages, print "ERROR" (uppercase) - POSIX standard.

  - Modified wcs.cards to explain and test free-format keyvalues, and
    also augmented the inline comment on illegal WCS cards that are to
    be rejected, and WCS-like cards to be discarded.  Added a header
    card with no inline comment.

  - Removed vsource from the wcsprm struct and added ssyssrc.

  - In wcsini(), fixed a problem with memory management for wcs.pv when
    NPVMAX is zero; likewise for wcs.ps and NPSMAX.

  - In wcsprt(), don't print auxiliary coordinate system information in
    arrays with zero address.

  - In wcss2p(), status == 9 (one or more invalid world coordinates) was
    not returned appropriately.

  - Renamed twcs1.c to twcs.c, and twcs2.c to twcsmix.c.

  - "Error status/code/number" is now referred to consistently as the
    "status return value".

  - Some vestiges of K&R C were removed: preprocessor definition of
    const, and K&R function prototypes.

* Fortran wrappers

  - New wrapper defined in wcs_f.c: wcssub_().  New test program,
    twcssub.f.

  - Renamed twcs1.f to twcs.f, and twcs2.f to twcsmix.f.

* PGSBOX

  - (No substantive changes.)

* Installation

  - Worked over the C, FORTRAN, and PGSBOX makefiles, in particular to
    make them all consistent.


WCSLIB version 3.5 (2004/06/28)
-------------------------------

* C library

  - WCSLIB now provides a function, wcspih() implemented as a Flex
    description, that parses a FITS image header, either that of a
    primary HDU or an image extension.  Given a character array
    containing the header it identifies and reads all WCS cards for
    the primary coordinate description and up to 26 alternate
    descriptions and returns this information as an array of wcsprm
    structs.  A service routine, wcsvfree(), is provided to free the
    memory allocated by wcspih().  The relevant header file for these
    functions is wcshdr.h.

    Test programs, tpih1 and tpih2, are provided to verify wcspih.  The
    first simply prints the contents of the structs using wcsprt().  The
    second uses cpgsbox() to draw coordinate graticules.  A FITS WCS
    test header has been developed to provide input to these test
    programs.  It is implemented as a list of card images, wcs.cards,
    one card per line, together with a program, tofits, that compiles
    these into a valid FITS file.  tpih1 uses its own code to read this,
    whereas tpih2 uses the fits_hdr2str() function from CFITSIO.

  - Removed twcsprt, tpih exercises wcsprt() much more thoroughly than
    twcsprt ever did.  Modified twcs1 to print the size of the various
    structs as twcsprt used to.

  - Although they are not used in any coordinate calculations, the
    wcsprm struct now provides data members for storing all of the
    auxiliary FITS WCS header cards defined in Papers I, II, and III,
    such as WCSNAMEa, EQUINOXa, and CNAMEia.  Members are also provided
    for storing the alternate descriptor code (the "a" in CTYPEia), and
    the binary table column number.  These are supported by the high
    level WCSLIB routines, wcsini(), wcscopy(), wcsfree(), and wcsprt().
    Refer to wcs.h for details.

  - The number of PVi_ma cards for which wcsini() allocates memory is
    now set by a global variable, NPVMAX (previously a C-preprocessor
    macro).  This defaults to 64 but may be changed by a new function,
    wcsnpv().  The wcsprm struct contains a new member, npvmax, that
    records the value of this number at the time the struct was
    initialized.  This is in addition to npv which records the actual
    number of cards that were encountered.

    Similarly, NPSMAX (default 8) is used for the number of PSi_ma
    cards, and it may be changed via wcsnps().

    The axis number, i, in the pvcard struct used for storing PVi_ma
    cards may now be set to 0 to indicate the latitude axis.

  - calloc() is now used in place of malloc() in allocating memory for
    arrays, and inclusion of malloc.h has been replaced with stdlib.h
    for all platforms.

    wcsfree() checks that wcs.flag != -1 before testing wcs.m_flag when
    freeing memory allocated by wcsini() in case the struct is
    uninitialized.  Similarly for linfree().

  - In prj.h, renamed C-preprocessor macros INI, PRT, SET, X2S and S2X
    to PRJINI, PRJPRT, PRJSET, PRJX2S and PRJS2X to reduce the
    likelihood of namespace clashes.  Similarly in spc.h.

    Also, in prj.c, changed the name of helper routine offset() to
    prjoff() to reduce the likelihood of global namespace conflicts.

  - In line with bonx2s() and bons2x(), bonset() now recognizes the
    equatorial case of Bonne's projection as Sanson-Flamsteed, mainly so
    that the auxiliary information in the prjprm struct more accurately
    reflects the truth.  Modified tcel2 to exercise this by using an
    equatorial Bonne projection in place of the Hammer-Aitov.

  - zpns2x() used prj.w[0] for bounds checking, though this had not been
    set by zpnset() for polynomials of degree N < 3.  Consequently,
    bounds checking for N < 3 was unreliable (reported by David Berry,
    STARLINK).

  - Changed some variable names in tscs2x(), cscx2s(), cscs2x(),
    qscx2s(), and qscs2x() to match Paper II, and likewise changed some
    inequality tests in qscs2x() without changing the results.

  - Minor tidying up of output formatting in prjprt().

  - Added the alternate version code to FITS WCS keywords mentioned in
    comments, e.g. CTYPEi changed to CTYPEia.

* Fortran wrappers

  - New wrappers defined in wcshdr_f.c: wcspih_() and wcsvfree_(), and
    also a new service function, wcsvcopy_().

    New test programs, TPIH1 and TPIH2, being analogues of tpih1 and
    tpih2.  Removed TWCSPRT.

  - In wcs_f.c, new wrappers wcsnpv_() and wcsnps_(); modified wcsput_()
    and wcsget_() to handle new members of the wcsprm struct.  Also
    modified wcsput_() to null-fill all char[] members of the wcsprm
    struct, and likewise wcsget_() to blank-fill them.

  - Modified wcs.inc to support changes to the wcsprm struct.

* PGSBOX

  - In PGSBOX, increased the dimension of the WORLD and XY vectors from
    2 to 9 to accomodate higher-dimensional coordinate representations
    of up to 9 elements.  Similarly for pgwcsl().  The assumption
    (presently) is that the first two world, and pixel, coordinate
    elements are the relevant ones; the others are all set to zero when
    pgwcsl() initializes and otherwise ignored.

    Assigned some variables in DATA to stop compiler messages about
    uninitialized variables.

  - Generalized the Makefile, bringing it into line with the WCSLIB
    Makefile, and adding separate targets for compiling and running the
    test programs.  The default target now simply compiles pgsbox.c and
    cpgsbox.c.  A separate target compiles pgwcsl.c and inserts it into
    ../C/libwcs.a.


WCSLIB version 3.4 (2004/02/11)
-------------------------------

* C library

  - In aitx2s(), apply the boundary condition 0.5 <= Z^2 <= 1 given
    after Eq. (109) in WCS Paper II to detect outlying pixels.

  - Fixed several special-case bugs in celset():

    1) For theta_0 = 90, in substituting the default value for phi_p
       (LONPOLE),

       a) for the special case when delta_0 = 90, celset() provided the
          wrong value (180 instead of 0),

       b) celset() neglected to add phi_0 (normally 0).

    2) For theta_0 != 90,

       a) for the special case when delta_0 = -90, celset() incorrectly
          computed delta_p (as theta_0 instead of -theta_0),

       b) for the special case when delta_p = +90 (or -90), celset()
          neglected to subtract (or add) phi_0 (normally 0).

    3) For |delta_0| = 90, celset() incorrectly allowed the particular,
       invalid, value of phi_p (LONPOLE) that put the other pole at the
       fiducial point.

    4) For theta_0 = 0, delta_0 = 0 LATPOLE determines delta_p
       completely.  For LATPOLE > 90 celset() now sets delta_p to 90,
       and for LATPOLE < -90 it sets it to -90.

  - Additional refinements in celset():

    1) cel->ref[2] is normalized in the range [-180,180].

    2) Account for rounding error in the computation of delta_p.

  - sphx2s() and sphs2x() incorrectly handled the "change in the origin
    of longitude" special case that arises when delta_p = -90, in the
    even more restrictive case where |theta| = 90 also; it applied
    Eq. (3) instead of Eq. (4) of Paper II.

  - Added a new test program, tcel2.c, to exercise celset() more
    thoroughly.  Renamed the original tcel.c to tcel1.c and modified the
    Makefile to suit.

* Fortran wrappers

  - (No changes.)

* PGSBOX

  - (No substantive changes.)


WCSLIB version 3.3 (2003/10/21)
-------------------------------

* C library

  - In celset(), the default value for phi_p (LONPOLE) is

       phi_p = phi_0 + ((delta_0 < theta_0) ?  180.0 : 0.0)

    Previously phi_0 (which is normally zero) was not added (reported by
    David Berry, STARLINK).

  - wcsprt() and linprt() now check that the structs have been
    initialized.

  - In wcsini(), when the wcsprm flag is -1 also set the linprm flag to
    -1 to force initialization of the memory managed by linset().

  - wcsset() now explicitly initializes the celprm and spcprm structs
    via celini() and spcini().

  - Fixed syntax errors in the macro definitions of linrev_errmsg and
    linfwd_errmsg.

  - In Makefile, added the -ansi option to gcc to force it to behave
    like a strict ANSI C compiler, specifically in setting the __STDC__
    preprocessor macro.

* Fortran wrappers

  - (No changes.)

* PGSBOX

  - PGSBOX now recognizes status returns -1, -2, and -3 from NLFUNC for
    opcodes +2 and +1 which cause it to accept the returned (x,y)
    coordinates but not consider them as one end of a crossing segment
    for labelling world coordinate 1, 2, or both.

  - PGSBOX now takes care not to lose vertical tick marks (and hence
    labels) at the left or right edge of the frame.  Likewise for
    horizontal tick marks at the top or bottom edge of the frame.

  - Tightened up the test in PGSBOX for cycles in angle to catch the
    case where the coordinate value spans a full 360 degrees.

  - PGSBOX will no longer accept frame crossings that are too oblique;
    floating point rounding errors may cause grid lines that should
    otherwise track along the frame to weave down it from side-to-side
    resulting in spurious crossing points.

  - Fixed a bug in pgwcsl_() for processing simple linear coordinates.

  - pgwcsl_() now returns error -2 if the latitude is outside -90 to +90
    for opcodes +2 and +1.

  - Amended the translation of status return codes from WCSLIB in
    pgwcsl_().

  - Provided a header file for pgwcsl_() (mainly for C++ usage).

  - Added extra test plots to PGTEST and cpgtest.

  - Added extra functionality to the Makefile.


WCSLIB version 3.2 (2003/09/09)
-------------------------------

* C library

  - Added the facility of setting the flag member of a wcsprm struct to
    -1 before calling wcsini() for the first time in order to initialize
    memory management.  Likewise for linprm and linini().

  - Renamed wcscpy() to wcscopy() to avoid a conflict with the Posix
    "wide character string" function of the same name (wchar.h).  In
    particular, this is used by the GNU C++ string class.

  - The higher level functions (wcs, cel, spc) no longer return
    prematurely if some of the input coordinate values are invalid.

  - All functions now test whether a null pointer for the particular
    struct (wcsprm, celprm, etc.) has been passed to them.

  - Function return codes have been rationalized into a consistent set
    within each of the wcs, cel, lin, prj, spc, and spx suites of
    functions.  Error messages to match these error codes are now
    encoded in a single character array, e.g. wcs_errmsg and prj_errmsg,
    instead of a separate array for each function.  Macro definitions
    for the older character arrays (e.g. wcsini_errmsg) have been
    provided for backward compatibility.

  - Declared prj_stat as extern in prj.h.

* Fortran wrappers

  - (No changes.)

* PGSBOX

  - Added an ENTRY point, PGLBOX, that provides a simplified interface
    to PGSBOX for linear axes without having to specify an NLFUNC or the
    associated parameters.


WCSLIB version 3.1 (2003/04/29)
-------------------------------

* C library

  - Added "global" and "divergent" prjprm struct informational members
    to record whether the projection is capable of mapping the whole
    sphere, and whether it is divergent in latitude.

  - Function cylfix() provided to fix WCS FITS header cards for
    malformed cylindrical projections (c.f. Paper II, Sect. 7.3.4).

  - Added support for CUNITi cards to wcsprm (but not currently
    implemented).

  - Added macro implementations of the trigd functions to wcstrig.h,
    enabled if WCSTRIG_MACRO is defined.

  - Improved printing of the WCSLIB structs.

  - Added macro definitions for the lengths of the WCSLIB structs
    measured in sizeof(int) units (mainly for the FORTRAN wrappers).

* Fortran wrappers

  - FORTRAN is now supported via a set of wrappers on the C library.
    Refer to the README file.

* PGSBOX



WCSLIB version 3.0 beta release (2003/04/01)
--------------------------------------------

* C library

  - Fully vectorized function interfaces (C preprocessor macros are
    available to implement the scalar interfaces of the proj.c, sph.c,
    and lin.c routines from WCSLIB 2.x).

  - Implementation of Paper II, Sect. 2.5: User-specified
    (phi0, theta0).

  - Implementation of Paper III (excluding "-TAB").

  - Memory management is now implemented in the upper-level (wcs.c)
    routines.

  - New extensible design should accomodate Paper IV (and any other)
    without further change to the function interfaces.

* PGSBOX

  - Added a C wrapper function, cpgsbox(), and C test/demo program,
    cpgtest, that duplicates PGTEST and serves as a C coding template.

  - Added calendar date axes.

  - Sped up the max/min search - if only tickmarks are required there is
    no need to search the interior of the image.

  - Return margin widths in CACHE(,NC).

  - Fixed a buglet that caused ticks at the frame edges to be skipped.

  - Return error 3 if CACHE overflows.

  - Adapted PGWCSL for WCSLIB 3.x - it is now a C function (for
    interfacing to WCSLIB) with a FORTRAN-like interface (for PGSBOX).


WCSLIB version 2.9 (2002/04/03)
-------------------------------

* C library

  - Fixed a bug with alias translation in wcsset().

  - Added a conditional compilation directive to lin.c for Apple's
    MacOSX.

* Fortran library

  - Fixed CUBEFACE handling in WCSSET.


WCSLIB version 2.8 (2001/11/16)
-------------------------------

* C library

  - Added support for the SZP projection with szpset(), szpfwd() and
    szprev(), and generalized AZP with support for the tilt parameter,
    gamma.

  - Added phi0 to the prjprm struct, this is set by the projection
    initialization routines along with theta0.

  - Fixed a problem in wcsmix() caused by numerical imprecision that
    could cause it not to recognize when convergence was reached; break
    out of the loop early if a discontinuity is detected.

  - Clarified the usage of vspan in the prologue to wcsmix().

  - Fixed comments relating to LATPOLE in the prologue to cel.c and
    tcel.c, and replaced references to LONGPOLE with LONPOLE.

  - Augmented the error reports in twcs2.

  - Modified projex() in tproj1 and prjplt() in tproj2 to make use of
    the information stored in the prjprm struct.

* Fortran library

  - Added support for the SZP projection with SZPSET, SZPFWD and SZPREV,
    and generalized AZP with support for the tilt parameter, gamma.

  - Changed the call sequence to PRJSET to return PHI0 along with
    THETA0.

  - Fixed a problem in WCSMIX caused by numerical imprecision that could
    cause it not to recognize when convergence was reached; break out of
    the loop early if a discontinuity is detected.

  - Clarified the usage of VSPAN in the prologue to WCSMIX.

  - Fixed comments relating to LATPOLE in the prologue to CEL and TCEL,
    and replaced references to LONGPOLE with LONPOLE.

  - Augmented the error reports in TWCS2.

  - Modified PROJEX in TPROJ1 and PRJPLT in TPROJ2 to use the generic
    driver routines PRJSET, PRJFWD and PRJREV.  PRJPLT also now uses the
    projection type encoded in PRJ(11).


WCSLIB version 2.7 (2001/02/19)
-------------------------------

* C library

  - Added generic driver routines prjset(), prjfwd() and prjrev().
    These invoke specific projection routines via the pointer-to-
    function elements, prjfwd and prjrev, transferred to the prjprm
    struct from celprm.

  - Added code (3-letter projection code) and theta0 (reference
    latitude) elements to prjprm.

  - The projection code for the Sanson-Flamsteed projection is now SFL.
    The upper-level routines, wcsset(), wcsfwd(), and wcsrev(),
    recognize GLS as an alias for this.

  - wcsset() now recognizes 'xyLN/xyLT' axis pairs.

  - Two bugs in the translation from NCP to SIN in wcsfwd() and wcsrev()
    were fixed: (1) the projection parameter was computed incorrectly
    and (2) they did not honour prj->flag set to -1 to disable strict
    bounds checking.

  - A bug in wcsmix() was fixed - it was relying on the wcsprm struct to
    have been initialized beforehand.

  - The test programs now use the cpgplot interface to PGPLOT, the old
    tpgc.c and tpgf.f wrappers have been removed.

* Fortran library

  - Added generic driver routines PRJSET, PRJFWD and PRJREV.  These are
    keyed to specific projection routines via the value of PRJ(11) which
    now differs for each projection.

  - The projection code for the Sanson-Flamsteed projection is now SFL.
    The upper-level routines, WCSSET, WCSFWD, and WCSREV, recognize GLS
    as an alias for this.

  - WCSSET now recognizes 'xyLN/xyLT' axis pairs.

  - A bug in the translation from NCP to SIN in WCSFWD and WCSREV was
    fixed; they did not honour PRJ(11) set to -1 to disable strict
    bounds checking.

  - A bug in WCSMIX was fixed - it was relying on the WCS array to have
    been initialized beforehand.


WCSLIB version 2.6 (2000/05/10)
-------------------------------

* C library

  - Check for invalid (x,y) in zearev().

  - In wcsmath.h, guard against prior definition of PI and other
    preprocessor variables.

* Fortran library

  - Check for invalid (X,Y) in ZEAREV.

  - Declare COSD and SIND in WCSFWD and WCSREV, reported by Clive Page
    (cgp@star.le.ac.uk).


WCSLIB version 2.5 (1999/12/14)
-------------------------------

* C library

  - Added copyright notice to header files and prefixed include guard
    names with "WCSLIB_".

  - Fixed cube face handling in wcsfwd() and wcsrev() (reported by
    Doug Mink, CfA).  Allow more general face layout in the inverse
    quadcube projections.

  - Fixed the problem in wcsmix() where it failed to find a valid
    solution when the solution point lay at a native pole of a
    projection in which the pole is represented as a finite interval.
    However, wcsmix() will only ever return one solution even when two
    or more valid solutions may exist.

  - wcsmix() now accepts viter in the range 5 - 10, the specified value
    will be pushed up or down into this range if necessary.

  - The projection routines for AZP, TAN, SIN, ZPN, and COP now return
    error 2 if (phi,theta) correspond to the overlapped (far) side of
    the projection.  This strict bounds checking can be switched off by
    setting prj->flag to -1 (rather than 0) when the projections are
    initialized.

  - The upper level routines, wcsset(), wcsfwd(), wcsrev(), and
    wcsmix(), now recognize the NCP projection and convert it to the
    equivalent SIN projection.  The lower level routines do not
    recognize NCP.

  - Extracted definitions of mathematical constants (PI etc.) from
    proj.h into wcsmath.h in order to avoid conflicts with their
    definition in math.h in some systems (such as Linux).

  - Describe the two alternate representations of the quadcube
    projections (i.e. faces laid out or stacked) in the prologue of
    wcs.c.

* Fortran library

  - Fixed cube face handling in WCSFWD and WCSREV, reported by Doug Mink
    (dmink@cfa.harvard.edu).  Allow more general face layout in the
    inverse quadcube projections.

  - Fixed the problem in WCSMIX where it failed to find a valid solution
    when the solution point lay at a native pole of a projection in
    which the pole is represented as a finite interval.  However, WCSMIX
    will only ever return one solution even when two or more valid
    solutions may exist.

  - WCSMIX now accepts VITER in the range 5 - 10, the specified value
    will be pushed up or down into this range if necessary.

  - The projection routines for AZP, TAN, SIN, ZPN, and COP now return
    error 2 if (phi,theta) correspond to the overlapped (far) side of
    the projection.  This strict bounds checking can be switched off by
    setting PRJ(11) to -1 (rather than 0) when the projections are
    initialized.

  - The upper level routines, WCSSET, WCSFWD, WCSREV, and WCSMIX, now
    recognize the NCP projection and convert it to the equivalent SIN
    projection.  The lower level routines do not recognize NCP.

  - Describe the two alternate representations of the quadcube
    projections (i.e. faces laid out or stacked) in the prologue of
    wcs.f.


WCSLIB version 2.4 (1996/09/23)
-------------------------------

* C library

  - In sinrev(), cscrev(), qscrev(), and tscrev(), return error 2 if
    (x,y) do not lie within the perimeter of the projection.  In
    sinrev(), stop the computation of phi for the "synthesis" projection
    being applied to the pure "orthographic" case (reported by
    David Berry, STARLINK).

  - (Internal change) Renamed variables l <-> m in the quadcube
    projections to accord with standard usage (and revised WCS draft
    paper).

* Fortran library

  - In SINREV, CSCREV, QSCREV, and TSCREV, return error 2 if (X,Y) do
    not lie within the perimeter of the projection.  In SINREV, stop the
    computation of PHI for the "synthesis" projection being applied to
    the pure "orthographic" case.  Reported by David Berry
    (dsb@ast.man.ac.uk).

  - (Internal change) Renamed variables L <-> M in the quadcube
    projections to accord with standard usage (and revised WCS draft
    paper).

  - (Internal change) Stopped PRJ(11) doing double service in any
    projection.  It is now set and tested for a specific magic value
    rather than simply being non-zero.


WCSLIB version 2.3 (1996/06/24)
-------------------------------

* C library

  - Fixed two bugs in zpnset().  The first led to an incorrect
    determination of the degree of the polynomial and would mainly have
    affected the efficiency of zpnrev().  The second affected the
    determination of the boundary of the projection but would only have
    been significant for projections with a point of inflection between
    9 and 10 degrees of the pole.  Reported by David Berry, STARLINK.

  - Replaced usage of alloca() in lin.c with malloc() and free() for
    portability as suggested by Klaus Banse, ESO (kbanse@eso.org).

  - Allow for C implementations that provide their own versions of
    cosd(), sind(), tand(), acosd(), asind(), atand(), and atan2d().
    From Klaus Banse, ESO (kbanse@eso.org).

  - Implemented the CUBEFACE axis for quadcube projections.

  - Made all function prototypes const-correct.

  - Adapted the header files to C++ usage.

  - Added a new test program, twcs1, to verify closure of wcsfwd() and
    wcsrev().  The old twcs test program is now called twcs2.

  - Added external arrays of error messages indexed by function return
    value.  For example, extern const char *wcsmix_errmsg[] for
    wcsmix().  Messages for the many proj.c functions are in
    prjfwd_errmsg[], etc.

* Fortran library

  - Implemented the CUBEFACE axis for quadcube projections.

  - Added a new test program, TWCS1, to verify closure of WCSFWD and
    WCSREV.  The old TWCS test program is now called TWCS2.


WCSLIB version 2.2 (1996/01/18)
-------------------------------

* C library

  - Amended the projection equations for the conics (COP, COD, COE, COO)
    and Bonne's projection (BON) to correctly handle southern hemisphere
    projections with PROJP1 < 0 (reported by Lindsay Davis, NOAO).
    Revised tproj1 and tproj2 to test such cases.

* Fortran library

  - Amended the projection equations for the conics (COP, COD, COE, COO)
    and Bonne's projection (BON) to correctly handle southern hemisphere
    projections with PROJP1 < 0 (reported by Lindsay Davis, NOAO).
    Revised TPROJ1 and TPROJ2 to test such cases.

  - Increased the dimension of the WCS array from WCS(0:2) to WCS(0:3)
    to allow for future handling of the CUBEFACE keyword - WCS(3) will
    store an index to the CUBEFACE axis.  This affects the call
    sequences of WCSSET, WCSFWD, WCSREV, and WCSMIX.


WCSLIB version 2.1 (1995/11/17)
-------------------------------

* C library

  The main change of interest to programmers is that of changed argument
  lists for wcsfwd() and wcsrev() as described below.

  - The WCS linear transformations are now implemented in WCSLIB,
    complete with matrix inverter.  The new files are lin.c, lin.h, and
    test program tlin.c.

  - Given either the celestial longitude or latitude plus an element of
    the pixel coordinate a new routine, wcsmix(), solves for the
    remaining elements by iterating on the unknown celestial coordinate
    element using wcsfwd().

  - The high level driver routines wcsfwd(), wcsrev(), and wcsmix() now
    apply the full WCS algorithm chain (except for pixel regularization
    table), including parsing the CTYPEn header cards and computing non-
    celestial elements of the world coordinate.  This required a change
    to their argument lists which now more closely reflect the sequence
    of algorithms applied.  A new routine, wcsset(), parses the CTYPEn.

  - The high level driver routines of WCSLIB 1.0 are available as
    intermediate level drivers celset(), celfwd(), and celrev(), but
    note that their argument lists have been extended to return native
    coordinates.  The related struct is now called celprm instead of
    wcsprm.

  - The reference point for conic projections is now at the midpoint of
    the standard parallels.  The FITS header cards PROJP1 and PROJP2 now
    give the half-sum (midpoint) and half-difference of the latitudes of
    the standard parallels; previously they gave the latitudes of the
    standard parallels themselves.  The change is reflected in this
    release of WCSLIB.

  - A bug in celset() (formerly wcsset()) that misapplied WCS draft
    equations 7 has been fixed (thanks to Rick Ebert IPAC/JPL and
    Lindsey Davis, NOAO for reporting this).  This affected the
    computation of Euler angles for the celestial coordinate
    transformation for those projections that have their reference point
    away from the native pole.  In investigating this a deficiency with
    the formalism was discovered that led to the introduction of a
    LATPOLE FITS header card which may be used to disambiguate where
    CRVAL1, CRVAL2, and LONGPOLE do not uniquely determine the latitude
    of the native pole.  The celprm struct (formerly wcsprm) has been
    extended to accomodate LATPOLE.

  - Default values of LONGPOLE and LATPOLE are now supported and their
    use is recommended where appropriate.

  - Numerical precision was being lost near the native poles in the SIN,
    AIR, and QSC projections and this has been recovered (reported by
    Lindsey Davis, NOAO).  Floating underflows in CSC are now avoided.

  - Numerical precision was also lost in certain circumstances in the
    spherical coordinate transformation routines and this has been
    fixed.

  - The test programs have been enhanced in various ways and the library
    has been validated on an SGI machine using both 32-bit and 64-bit
    compilers.

* Fortran library

  The main change of interest to programmers is that of changed call
  sequences for WCSFWD and WCSREV as described below.

  - The WCS linear transformations are now implemented in WCSLIB,
    complete with matrix inverter.  The new files are lin.f and test
    program tlin.f.

  - Given either the celestial longitude or latitude plus an element of
    the pixel coordinate a new routine, WCSMIX, solves for the remaining
    elements by iterating on the unknown celestial coordinate element
    using WCSFWD.

  - The high level driver routines WCSFWD, WCSREV, and WCSMIX now apply
    the full WCS algorithm chain (except for pixel regularization
    table), including parsing the CTYPEn header cards and computing non-
    celestial elements of the world coordinate.  This required a change
    to their call sequences which now more closely reflect the sequence
    of algorithms applied.  A new routine, WCSSET, parses the CTYPEn.

  - The high level driver routines of WCSLIB 1.0 are available as
    intermediate level drivers CELSET, CELFWD, and CELREV, but note
    that their call sequences have been extended to return native
    coordinates.  The related parameter array is now called CEL instead
    of WCS.

  - The reference point for conic projections is now at the midpoint of
    the standard parallels.  The FITS header cards PROJP1 and PROJP2 now
    give the half-sum (midpoint) and half-difference of the latitudes of
    the standard parallels; previously they gave the latitudes of the
    standard parallels themselves.  The change is reflected in this
    release of WCSLIB.

  - A bug in CELSET (formerly WCSSET) that misapplied WCS draft
    equations 7 has been fixed (thanks to Rick Ebert IPAC/JPL and
    Lindsey Davis, NOAO for reporting this).  This affected the
    computation of Euler angles for the celestial coordinate
    transformation for those projections that have their reference point
    away from the native pole.  In investigating this a deficiency with
    the formalism was discovered that led to the introduction of a
    LATPOLE FITS header card which may be used to disambiguate where
    CRVAL1, CRVAL2, and LONGPOLE do not uniquely determine the latitude
    of the native pole.  The CEL parameter array (formerly WCS) has been
    extended to accomodate LATPOLE as CEL(4), and the flag variable is
    now CEL(5) (formerly WCS(4)).

  - Default values of LONGPOLE and LATPOLE are now supported and their
    use is recommended where appropriate.

  - Numerical precision was being lost near the native poles in the SIN,
    AIR, and QSC projections and this has been recovered (reported by
    Lindsey Davis, NOAO).  Floating underflows in CSC are now avoided.

  - Numerical precision was also lost in certain circumstances in the
    spherical coordinate transformation routines and this has been
    fixed.

  - The test programs have been enhanced in various ways and the
    library has been validated on an SGI machine using both 32-bit and
    64-bit compilers.


WCSLIB version 1.0 (1995/01/31)
-------------------------------

* C library

  Initial release.

* Fortran library

  Initial release.

------------------------------------------------------------------------
$Id: CHANGES,v 7.4 2021/01/31 02:24:52 mcalabre Exp $