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wcs.h
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/*============================================================================
WCSLIB 8.4 - an implementation of the FITS WCS standard.
Copyright (C) 1995-2024, Mark Calabretta
This file is part of WCSLIB.
WCSLIB is free software: you can redistribute it and/or modify it under the
terms of the GNU Lesser General Public License as published by the Free
Software Foundation, either version 3 of the License, or (at your option)
any later version.
WCSLIB is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for
more details.
You should have received a copy of the GNU Lesser General Public License
along with WCSLIB. If not, see http://www.gnu.org/licenses.
Author: Mark Calabretta, Australia Telescope National Facility, CSIRO.
http://www.atnf.csiro.au/people/Mark.Calabretta
$Id: wcs.h,v 8.4 2024/10/28 13:56:16 mcalabre Exp $
*=============================================================================
*
* WCSLIB 8.4 - C routines that implement the FITS World Coordinate System
* (WCS) standard. Refer to the README file provided with WCSLIB for an
* overview of the library.
*
*
* Summary of the wcs routines
* ---------------------------
* Routines in this suite implement the FITS World Coordinate System (WCS)
* standard which defines methods to be used for computing world coordinates
* from image pixel coordinates, and vice versa. The standard, and proposed
* extensions for handling distortions, are described in
*
= "Representations of world coordinates in FITS",
= Greisen, E.W., & Calabretta, M.R. 2002, A&A, 395, 1061 (WCS Paper I)
=
= "Representations of celestial coordinates in FITS",
= Calabretta, M.R., & Greisen, E.W. 2002, A&A, 395, 1077 (WCS Paper II)
=
= "Representations of spectral coordinates in FITS",
= Greisen, E.W., Calabretta, M.R., Valdes, F.G., & Allen, S.L.
= 2006, A&A, 446, 747 (WCS Paper III)
=
= "Representations of distortions in FITS world coordinate systems",
= Calabretta, M.R. et al. (WCS Paper IV, draft dated 2004/04/22),
= available from http://www.atnf.csiro.au/people/Mark.Calabretta
=
= "Mapping on the HEALPix grid",
= Calabretta, M.R., & Roukema, B.F. 2007, MNRAS, 381, 865 (WCS Paper V)
=
= "Representing the 'Butterfly' Projection in FITS -- Projection Code XPH",
= Calabretta, M.R., & Lowe, S.R. 2013, PASA, 30, e050 (WCS Paper VI)
=
= "Representations of time coordinates in FITS -
= Time and relative dimension in space",
= Rots, A.H., Bunclark, P.S., Calabretta, M.R., Allen, S.L.,
= Manchester, R.N., & Thompson, W.T. 2015, A&A, 574, A36 (WCS Paper VII)
*
* These routines are based on the wcsprm struct which contains all information
* needed for the computations. The struct contains some members that must be
* set by the user, and others that are maintained by these routines, somewhat
* like a C++ class but with no encapsulation.
*
* wcsnpv(), wcsnps(), wcsini(), wcsinit(), wcssub(), wcsfree(), and wcstrim(),
* are provided to manage the wcsprm struct, wcssize() computes its total size
* including allocated memory, wcsenq() returns information about the state of
* the struct, and wcsprt() prints its contents. wcscopy(), which does a deep
* copy of one wcsprm struct to another, is defined as a preprocessor macro
* function that invokes wcssub().
*
* wcsperr() prints the error message(s) (if any) stored in a wcsprm struct,
* and the linprm, celprm, prjprm, spcprm, and tabprm structs that it contains.
*
* A setup routine, wcsset(), computes intermediate values in the wcsprm struct
* from parameters in it that were supplied by the user. The struct always
* needs to be set up by wcsset() but this need not be called explicitly -
* refer to the explanation of wcsprm::flag.
*
* wcsp2s() and wcss2p() implement the WCS world coordinate transformations.
* In fact, they are high level driver routines for the WCS linear,
* logarithmic, celestial, spectral and tabular transformation routines
* described in lin.h, log.h, cel.h, spc.h and tab.h.
*
* Given either the celestial longitude or latitude plus an element of the
* pixel coordinate a hybrid routine, wcsmix(), iteratively solves for the
* unknown elements.
*
* wcsccs() changes the celestial coordinate system of a wcsprm struct, for
* example, from equatorial to galactic, and wcssptr() translates the spectral
* axis. For example, a 'FREQ' axis may be translated into 'ZOPT-F2W' and vice
* versa.
*
* wcslib_version() returns the WCSLIB version number.
*
* Quadcube projections:
* ---------------------
* The quadcube projections (TSC, CSC, QSC) may be represented in FITS in
* either of two ways:
*
* a: The six faces may be laid out in one plane and numbered as follows:
*
= 0
=
= 4 3 2 1 4 3 2
=
= 5
*
* Faces 2, 3 and 4 may appear on one side or the other (or both). The
* world-to-pixel routines map faces 2, 3 and 4 to the left but the
* pixel-to-world routines accept them on either side.
*
* b: The "COBE" convention in which the six faces are stored in a
* three-dimensional structure using a CUBEFACE axis indexed from
* 0 to 5 as above.
*
* These routines support both methods; wcsset() determines which is being
* used by the presence or absence of a CUBEFACE axis in ctype[]. wcsp2s()
* and wcss2p() translate the CUBEFACE axis representation to the single
* plane representation understood by the lower-level WCSLIB projection
* routines.
*
*
* wcsnpv() - Memory allocation for PVi_ma
* ---------------------------------------
* wcsnpv() sets or gets the value of NPVMAX (default 64). This global
* variable controls the number of pvcard structs, for holding PVi_ma
* keyvalues, that wcsini() should allocate space for. It is also used by
* wcsinit() as the default value of npvmax.
*
* PLEASE NOTE: This function is not thread-safe.
*
* Given:
* n int Value of NPVMAX; ignored if < 0. Use a value less
* than zero to get the current value.
*
* Function return value:
* int Current value of NPVMAX.
*
*
* wcsnps() - Memory allocation for PSi_ma
* ---------------------------------------
* wcsnps() sets or gets the value of NPSMAX (default 8). This global variable
* controls the number of pscard structs, for holding PSi_ma keyvalues, that
* wcsini() should allocate space for. It is also used by wcsinit() as the
* default value of npsmax.
*
* PLEASE NOTE: This function is not thread-safe.
*
* Given:
* n int Value of NPSMAX; ignored if < 0. Use a value less
* than zero to get the current value.
*
* Function return value:
* int Current value of NPSMAX.
*
*
* wcsini() - Default constructor for the wcsprm struct
* ----------------------------------------------------
* wcsini() is a thin wrapper on wcsinit(). It invokes it with npvmax,
* npsmax, and ndpmax set to -1 which causes it to use the values of the
* global variables NDPMAX, NPSMAX, and NDPMAX. It is thereby potentially
* thread-unsafe if these variables are altered dynamically via wcsnpv(),
* wcsnps(), and disndp(). Use wcsinit() for a thread-safe alternative in
* this case.
*
*
* wcsinit() - Default constructor for the wcsprm struct
* -----------------------------------------------------
* wcsinit() optionally allocates memory for arrays in a wcsprm struct and sets
* all members of the struct to default values.
*
* PLEASE NOTE: every wcsprm struct should be initialized by wcsinit(),
* possibly repeatedly. On the first invokation, and only the first
* invokation, wcsprm::flag must be set to -1 to initialize memory management,
* regardless of whether wcsinit() will actually be used to allocate memory.
*
* Given:
* alloc int If true, allocate memory unconditionally for the
* crpix, etc. arrays. Please note that memory is never
* allocated by wcsinit() for the auxprm, tabprm, nor
* wtbarr structs.
*
* If false, it is assumed that pointers to these arrays
* have been set by the user except if they are null
* pointers in which case memory will be allocated for
* them regardless. (In other words, setting alloc true
* saves having to initalize these pointers to zero.)
*
* naxis int The number of world coordinate axes. This is used to
* determine the length of the various wcsprm vectors and
* matrices and therefore the amount of memory to
* allocate for them.
*
* Given and returned:
* wcs struct wcsprm*
* Coordinate transformation parameters.
*
* Note that, in order to initialize memory management,
* wcsprm::flag should be set to -1 when wcs is
* initialized for the first time (memory leaks may
* result if it had already been initialized).
*
* Given:
* npvmax int The number of PVi_ma keywords to allocate space for.
* If set to -1, the value of the global variable NPVMAX
* will be used. This is potentially thread-unsafe if
* wcsnpv() is being used dynamically to alter its value.
*
* npsmax int The number of PSi_ma keywords to allocate space for.
* If set to -1, the value of the global variable NPSMAX
* will be used. This is potentially thread-unsafe if
* wcsnps() is being used dynamically to alter its value.
*
* ndpmax int The number of DPja or DQia keywords to allocate space
* for. If set to -1, the value of the global variable
* NDPMAX will be used. This is potentially
* thread-unsafe if disndp() is being used dynamically to
* alter its value.
*
* Function return value:
* int Status return value:
* 0: Success.
* 1: Null wcsprm pointer passed.
* 2: Memory allocation failed.
*
* For returns > 1, a detailed error message is set in
* wcsprm::err if enabled, see wcserr_enable().
*
*
* wcsauxi() - Default constructor for the auxprm struct
* -----------------------------------------------------
* wcsauxi() optionally allocates memory for an auxprm struct, attaches it to
* wcsprm, and sets all members of the struct to default values.
*
* Given:
* alloc int If true, allocate memory unconditionally for the
* auxprm struct.
*
* If false, it is assumed that wcsprm::aux has already
* been set to point to an auxprm struct, in which case
* the user is responsible for managing that memory.
* However, if wcsprm::aux is a null pointer, memory will
* be allocated regardless. (In other words, setting
* alloc true saves having to initalize the pointer to
* zero.)
*
* Given and returned:
* wcs struct wcsprm*
* Coordinate transformation parameters.
*
* Function return value:
* int Status return value:
* 0: Success.
* 1: Null wcsprm pointer passed.
* 2: Memory allocation failed.
*
*
* wcssub() - Subimage extraction routine for the wcsprm struct
* ------------------------------------------------------------
* wcssub() extracts the coordinate description for a subimage from a wcsprm
* struct. It does a deep copy, using wcsinit() to allocate memory for its
* arrays if required. Only the "information to be provided" part of the
* struct is extracted. Consequently, wcsset() need not have been, and won't
* be invoked on the struct from which the subimage is extracted. A call to
* wcsset() is required to set up the subimage struct.
*
* The world coordinate system of the subimage must be separable in the sense
* that the world coordinates at any point in the subimage must depend only on
* the pixel coordinates of the axes extracted. In practice, this means that
* the linear transformation matrix of the original image must not contain
* non-zero off-diagonal terms that associate any of the subimage axes with any
* of the non-subimage axes. Likewise, if any distortions are associated with
* the subimage axes, they must not depend on any of the axes that are not
* being extracted.
*
* Note that while the required elements of the tabprm array are extracted, the
* wtbarr array is not. (Thus it is not appropriate to call wcssub() after
* wcstab() but before filling the tabprm structs - refer to wcshdr.h.)
*
* wcssub() can also add axes to a wcsprm struct. The new axes will be created
* using the defaults set by wcsinit() which produce a simple, unnamed, linear
* axis with world coordinate equal to the pixel coordinate. These default
* values can be changed afterwards, before invoking wcsset().
*
* Given:
* alloc int If true, allocate memory for the crpix, etc. arrays in
* the destination. Otherwise, it is assumed that
* pointers to these arrays have been set by the user
* except if they are null pointers in which case memory
* will be allocated for them regardless.
*
* wcssrc const struct wcsprm*
* Struct to extract from.
*
* Given and returned:
* nsub int*
* axes int[] Vector of length *nsub containing the image axis
* numbers (1-relative) to extract. Order is
* significant; axes[0] is the axis number of the input
* image that corresponds to the first axis in the
* subimage, etc.
*
* Use an axis number of 0 to create a new axis using
* the defaults set by wcsinit(). They can be changed
* later.
*
* nsub (the pointer) may be set to zero, and so also may
* *nsub, which is interpreted to mean all axes in the
* input image; the number of axes will be returned if
* nsub != 0x0. axes itself (the pointer) may be set to
* zero to indicate the first *nsub axes in their
* original order.
*
* Set both nsub (or *nsub) and axes to zero to do a deep
* copy of one wcsprm struct to another.
*
* Subimage extraction by coordinate axis type may be
* done by setting the elements of axes[] to the
* following special preprocessor macro values:
*
* WCSSUB_LONGITUDE: Celestial longitude.
* WCSSUB_LATITUDE: Celestial latitude.
* WCSSUB_CUBEFACE: Quadcube CUBEFACE axis.
* WCSSUB_SPECTRAL: Spectral axis.
* WCSSUB_STOKES: Stokes axis.
* WCSSUB_TIME: Time axis.
*
* Refer to the notes (below) for further usage examples.
*
* On return, *nsub will be set to the number of axes in
* the subimage; this may be zero if there were no axes
* of the required type(s) (in which case no memory will
* be allocated). axes[] will contain the axis numbers
* that were extracted, or 0 for newly created axes. The
* vector length must be sufficient to contain all axis
* numbers. No checks are performed to verify that the
* coordinate axes are consistent, this is done by
* wcsset().
*
* wcsdst struct wcsprm*
* Struct describing the subimage. wcsprm::flag should
* be set to -1 if wcsdst was not previously initialized
* (memory leaks may result if it was previously
* initialized).
*
* Function return value:
* int Status return value:
* 0: Success.
* 1: Null wcsprm pointer passed.
* 2: Memory allocation failed.
* 12: Invalid subimage specification.
* 13: Non-separable subimage coordinate system.
*
* For returns > 1, a detailed error message is set in
* wcsprm::err if enabled, see wcserr_enable().
*
* Notes:
* 1: Combinations of subimage axes of particular types may be extracted in
* the same order as they occur in the input image by combining
* preprocessor codes, for example
*
= *nsub = 1;
= axes[0] = WCSSUB_LONGITUDE | WCSSUB_LATITUDE | WCSSUB_SPECTRAL;
*
* would extract the longitude, latitude, and spectral axes in the same
* order as the input image. If one of each were present, *nsub = 3 would
* be returned.
*
* For convenience, WCSSUB_CELESTIAL is defined as the combination
* WCSSUB_LONGITUDE | WCSSUB_LATITUDE | WCSSUB_CUBEFACE.
*
* The codes may also be negated to extract all but the types specified,
* for example
*
= *nsub = 4;
= axes[0] = WCSSUB_LONGITUDE;
= axes[1] = WCSSUB_LATITUDE;
= axes[2] = WCSSUB_CUBEFACE;
= axes[3] = -(WCSSUB_SPECTRAL | WCSSUB_STOKES);
*
* The last of these specifies all axis types other than spectral or
* Stokes. Extraction is done in the order specified by axes[] a
* longitude axis (if present) would be extracted first (via axes[0]) and
* not subsequently (via axes[3]). Likewise for the latitude and cubeface
* axes in this example.
*
* From the foregoing, it is apparent that the value of *nsub returned may
* be less than or greater than that given. However, it will never exceed
* the number of axes in the input image (plus the number of newly-created
* axes if any were specified on input).
*
*
* wcscompare() - Compare two wcsprm structs for equality
* ------------------------------------------------------
* wcscompare() compares two wcsprm structs for equality.
*
* Given:
* cmp int A bit field controlling the strictness of the
* comparison. When 0, all fields must be identical.
*
* The following constants may be or'ed together to
* relax the comparison:
* WCSCOMPARE_ANCILLARY: Ignore ancillary keywords
* that don't change the WCS transformation, such
* as DATE-OBS or EQUINOX.
* WCSCOMPARE_TILING: Ignore integral differences in
* CRPIXja. This is the 'tiling' condition, where
* two WCSes cover different regions of the same
* map projection and align on the same map grid.
* WCSCOMPARE_CRPIX: Ignore any differences at all in
* CRPIXja. The two WCSes cover different regions
* of the same map projection but may not align on
* the same map grid. Overrides WCSCOMPARE_TILING.
*
* tol double Tolerance for comparison of floating-point values.
* For example, for tol == 1e-6, all floating-point
* values in the structs must be equal to the first 6
* decimal places. A value of 0 implies exact equality.
*
* wcs1 const struct wcsprm*
* The first wcsprm struct to compare.
*
* wcs2 const struct wcsprm*
* The second wcsprm struct to compare.
*
* Returned:
* equal int* Non-zero when the given structs are equal.
*
* Function return value:
* int Status return value:
* 0: Success.
* 1: Null pointer passed.
*
*
* wcscopy() macro - Copy routine for the wcsprm struct
* ----------------------------------------------------
* wcscopy() does a deep copy of one wcsprm struct to another. As of
* WCSLIB 3.6, it is implemented as a preprocessor macro that invokes
* wcssub() with the nsub and axes pointers both set to zero.
*
*
* wcsfree() - Destructor for the wcsprm struct
* --------------------------------------------
* wcsfree() frees memory allocated for the wcsprm arrays by wcsinit() and/or
* wcsset(). wcsinit() records the memory it allocates and wcsfree() will only
* attempt to free this.
*
* PLEASE NOTE: wcsfree() must not be invoked on a wcsprm struct that was not
* initialized by wcsinit().
*
* Given and returned:
* wcs struct wcsprm*
* Coordinate transformation parameters.
*
* Function return value:
* int Status return value:
* 0: Success.
* 1: Null wcsprm pointer passed.
*
*
* wcstrim() - Free unused arrays in the wcsprm struct
* ---------------------------------------------------
* wcstrim() frees memory allocated by wcsinit() for arrays in the wcsprm
* struct that remains unused after it has been set up by wcsset().
*
* The free'd array members are associated with FITS WCS keyrecords that are
* rarely used and usually just bloat the struct: wcsprm::crota, wcsprm::colax,
* wcsprm::cname, wcsprm::crder, wcsprm::csyer, wcsprm::czphs, and
* wcsprm::cperi. If unused, wcsprm::pv, wcsprm::ps, and wcsprm::cd are also
* freed.
*
* Once these arrays have been freed, a test such as
=
= if (!undefined(wcs->cname[i])) {...}
=
* must be protected as follows
=
= if (wcs->cname && !undefined(wcs->cname[i])) {...}
=
* In addition, if wcsprm::npv is non-zero but less than wcsprm::npvmax, then
* the unused space in wcsprm::pv will be recovered (using realloc()).
* Likewise for wcsprm::ps.
*
* Given and returned:
* wcs struct wcsprm*
* Coordinate transformation parameters.
*
* Function return value:
* int Status return value:
* 0: Success.
* 1: Null wcsprm pointer passed.
* 14: wcsprm struct is unset.
*
*
* wcssize() - Compute the size of a wcsprm struct
* -----------------------------------------------
* wcssize() computes the full size of a wcsprm struct, including allocated
* memory.
*
* Given:
* wcs const struct wcsprm*
* Coordinate transformation parameters.
*
* If NULL, the base size of the struct and the allocated
* size are both set to zero.
*
* Returned:
* sizes int[2] The first element is the base size of the struct as
* returned by sizeof(struct wcsprm). The second element
* is the total allocated size, in bytes, assuming that
* the allocation was done by wcsini(). This figure
* includes memory allocated for members of constituent
* structs, such as wcsprm::lin.
*
* It is not an error for the struct not to have been set
* up via wcsset(), which normally results in additional
* memory allocation.
*
* Function return value:
* int Status return value:
* 0: Success.
*
*
* auxsize() - Compute the size of a auxprm struct
* -----------------------------------------------
* auxsize() computes the full size of an auxprm struct, including allocated
* memory.
*
* Given:
* aux const struct auxprm*
* Auxiliary coordinate information.
*
* If NULL, the base size of the struct and the allocated
* size are both set to zero.
*
* Returned:
* sizes int[2] The first element is the base size of the struct as
* returned by sizeof(struct auxprm). The second element
* is the total allocated size, in bytes, currently zero.
*
* Function return value:
* int Status return value:
* 0: Success.
*
*
* wcsenq() - enquire about the state of a wcsprm struct
* -----------------------------------------------------
* wcsenq() may be used to obtain information about the state of a wcsprm
* struct. The function returns a true/false answer for the enquiry asked.
*
* Given:
* wcs const struct wcsprm*
* Coordinate transformation parameters.
*
* enquiry int Enquiry according to the following parameters:
* WCSENQ_MEM: memory in the struct is being managed by
* WCSLIB (see wcsini()).
* WCSENQ_SET: the struct has been set up by wcsset().
* WCSENQ_BYP: the struct is in bypass mode (see
* wcsset()).
* WCSENQ_CHK: the struct is self-consistent in that
* no changes have been made to any of the
* "parameters to be given" since the last
* call to wcsset().
* These may be combined by logical OR, e.g.
* WCSENQ_MEM | WCSENQ_SET. The enquiry result will be
* the logical AND of the individual results.
*
* Function return value:
* int Enquiry result:
* 0: False.
* 1: True.
*
*
* wcsprt() - Print routine for the wcsprm struct
* ----------------------------------------------
* wcsprt() prints the contents of a wcsprm struct using wcsprintf(). Mainly
* intended for diagnostic purposes.
*
* Given:
* wcs const struct wcsprm*
* Coordinate transformation parameters.
*
* Function return value:
* int Status return value:
* 0: Success.
* 1: Null wcsprm pointer passed.
*
*
* wcsperr() - Print error messages from a wcsprm struct
* -----------------------------------------------------
* wcsperr() prints the error message(s), if any, stored in a wcsprm struct,
* and the linprm, celprm, prjprm, spcprm, and tabprm structs that it contains.
* If there are no errors then nothing is printed. It uses wcserr_prt(), q.v.
*
* Given:
* wcs const struct wcsprm*
* Coordinate transformation parameters.
*
* prefix const char *
* If non-NULL, each output line will be prefixed with
* this string.
*
* Function return value:
* int Status return value:
* 0: Success.
* 1: Null wcsprm pointer passed.
*
*
* wcsbchk() - Enable/disable bounds checking
* ------------------------------------------
* wcsbchk() is used to control bounds checking in the projection routines.
* Note that wcsset() always enables bounds checking. wcsbchk() will invoke
* wcsset() on the wcsprm struct beforehand if necessary.
*
* Given and returned:
* wcs struct wcsprm*
* Coordinate transformation parameters.
*
* Given:
* bounds int If bounds&1 then enable strict bounds checking for the
* spherical-to-Cartesian (s2x) transformation for the
* AZP, SZP, TAN, SIN, ZPN, and COP projections.
*
* If bounds&2 then enable strict bounds checking for the
* Cartesian-to-spherical (x2s) transformation for the
* HPX and XPH projections.
*
* If bounds&4 then enable bounds checking on the native
* coordinates returned by the Cartesian-to-spherical
* (x2s) transformations using prjchk().
*
* Zero it to disable all checking.
*
* Function return value:
* int Status return value:
* 0: Success.
* 1: Null wcsprm pointer passed.
*
*
* wcsset() - Setup routine for the wcsprm struct
* ----------------------------------------------
* wcsset() sets up a wcsprm struct according to information supplied within
* it (refer to the description of the wcsprm struct).
*
* wcsset() recognizes the NCP projection and converts it to the equivalent SIN
* projection and likewise translates GLS into SFL. It also translates the
* AIPS spectral types ('FREQ-LSR', 'FELO-HEL', etc.), possibly changing the
* input header keywords wcsprm::ctype and/or wcsprm::specsys if necessary.
*
* Note that this routine need not be called directly; it will be invoked by
* wcsp2s() and wcss2p() if the wcsprm::flag is anything other than a
* predefined magic value.
*
* wcsset() normally operates regardless of the value of wcsprm::flag; i.e.
* even if a struct was previously set up it will be reset unconditionally.
* However, a wcsprm struct may be put into "bypass" mode by invoking wcsset()
* initially with wcsprm::flag == 1 (rather than 0). wcsset() will return
* immediately if invoked on a struct in that state. To take a struct out of
* bypass mode, simply reset wcsprm::flag to zero. See also wcsenq().
*
* Given and returned:
* wcs struct wcsprm*
* Coordinate transformation parameters.
*
* Function return value:
* int Status return value:
* 0: Success.
* 1: Null wcsprm pointer passed.
* 2: Memory allocation failed.
* 3: Linear transformation matrix is singular.
* 4: Inconsistent or unrecognized coordinate axis
* types.
* 5: Invalid parameter value.
* 6: Invalid coordinate transformation parameters.
* 7: Ill-conditioned coordinate transformation
* parameters.
*
* For returns > 1, a detailed error message is set in
* wcsprm::err if enabled, see wcserr_enable().
*
* Notes:
* 1: wcsset() always enables strict bounds checking in the projection
* routines (via a call to prjini()). Use wcsbchk() to modify
* bounds-checking after wcsset() is invoked.
*
*
* wcsp2s() - Pixel-to-world transformation
* ----------------------------------------
* wcsp2s() transforms pixel coordinates to world coordinates.
*
* Given and returned:
* wcs struct wcsprm*
* Coordinate transformation parameters.
*
* Given:
* ncoord,
* nelem int The number of coordinates, each of vector length
* nelem but containing wcs.naxis coordinate elements.
* Thus nelem must equal or exceed the value of the
* NAXIS keyword unless ncoord == 1, in which case nelem
* is not used.
*
* pixcrd const double[ncoord][nelem]
* Array of pixel coordinates.
*
* Returned:
* imgcrd double[ncoord][nelem]
* Array of intermediate world coordinates. For
* celestial axes, imgcrd[][wcs.lng] and
* imgcrd[][wcs.lat] are the projected x-, and
* y-coordinates in pseudo "degrees". For spectral
* axes, imgcrd[][wcs.spec] is the intermediate spectral
* coordinate, in SI units. For time axes,
* imgcrd[][wcs.time] is the intermediate time
* coordinate.
*
* phi,theta double[ncoord]
* Longitude and latitude in the native coordinate system
* of the projection [deg].
*
* world double[ncoord][nelem]
* Array of world coordinates. For celestial axes,
* world[][wcs.lng] and world[][wcs.lat] are the
* celestial longitude and latitude [deg]. For spectral
* axes, world[][wcs.spec] is the spectral coordinate, in
* SI units. For time axes, world[][wcs.time] is the
* time coordinate.
*
* stat int[ncoord]
* Status return value for each coordinate:
* 0: Success.
* 1+: A bit mask indicating invalid pixel coordinate
* element(s).
*
* Function return value:
* int Status return value:
* 0: Success.
* 1: Null wcsprm pointer passed.
* 2: Memory allocation failed.
* 3: Linear transformation matrix is singular.
* 4: Inconsistent or unrecognized coordinate axis
* types.
* 5: Invalid parameter value.
* 6: Invalid coordinate transformation parameters.
* 7: Ill-conditioned coordinate transformation
* parameters.
* 8: One or more of the pixel coordinates were
* invalid, as indicated by the stat vector.
*
* For returns > 1, a detailed error message is set in
* wcsprm::err if enabled, see wcserr_enable().
*
*
* wcss2p() - World-to-pixel transformation
* ----------------------------------------
* wcss2p() transforms world coordinates to pixel coordinates.
*
* Given and returned:
* wcs struct wcsprm*
* Coordinate transformation parameters.
*
* Given:
* ncoord,
* nelem int The number of coordinates, each of vector length nelem
* but containing wcs.naxis coordinate elements. Thus
* nelem must equal or exceed the value of the NAXIS
* keyword unless ncoord == 1, in which case nelem is not
* used.
*
* world const double[ncoord][nelem]
* Array of world coordinates. For celestial axes,
* world[][wcs.lng] and world[][wcs.lat] are the
* celestial longitude and latitude [deg]. For spectral
* axes, world[][wcs.spec] is the spectral coordinate, in
* SI units. For time axes, world[][wcs.time] is the
* time coordinate.
*
* Returned:
* phi,theta double[ncoord]
* Longitude and latitude in the native coordinate
* system of the projection [deg].
*
* imgcrd double[ncoord][nelem]
* Array of intermediate world coordinates. For
* celestial axes, imgcrd[][wcs.lng] and
* imgcrd[][wcs.lat] are the projected x-, and
* y-coordinates in pseudo "degrees". For quadcube
* projections with a CUBEFACE axis the face number is
* also returned in imgcrd[][wcs.cubeface]. For
* spectral axes, imgcrd[][wcs.spec] is the intermediate
* spectral coordinate, in SI units. For time axes,
* imgcrd[][wcs.time] is the intermediate time
* coordinate.
*
* pixcrd double[ncoord][nelem]
* Array of pixel coordinates.
*
* stat int[ncoord]
* Status return value for each coordinate:
* 0: Success.
* 1+: A bit mask indicating invalid world coordinate
* element(s).
*
* Function return value:
* int Status return value:
* 0: Success.
* 1: Null wcsprm pointer passed.
* 2: Memory allocation failed.
* 3: Linear transformation matrix is singular.
* 4: Inconsistent or unrecognized coordinate axis
* types.
* 5: Invalid parameter value.
* 6: Invalid coordinate transformation parameters.
* 7: Ill-conditioned coordinate transformation
* parameters.
* 9: One or more of the world coordinates were
* invalid, as indicated by the stat vector.
*
* For returns > 1, a detailed error message is set in
* wcsprm::err if enabled, see wcserr_enable().
*
*
* wcsmix() - Hybrid coordinate transformation
* -------------------------------------------
* wcsmix(), given either the celestial longitude or latitude plus an element
* of the pixel coordinate, solves for the remaining elements by iterating on
* the unknown celestial coordinate element using wcss2p(). Refer also to the
* notes below.
*
* Given and returned:
* wcs struct wcsprm*
* Indices for the celestial coordinates obtained
* by parsing the wcsprm::ctype[].
*
* Given:
* mixpix int Which element of the pixel coordinate is given.
*
* mixcel int Which element of the celestial coordinate is given:
* 1: Celestial longitude is given in
* world[wcs.lng], latitude returned in
* world[wcs.lat].
* 2: Celestial latitude is given in
* world[wcs.lat], longitude returned in
* world[wcs.lng].
*
* vspan const double[2]
* Solution interval for the celestial coordinate [deg].
* The ordering of the two limits is irrelevant.
* Longitude ranges may be specified with any convenient
* normalization, for example [-120,+120] is the same as
* [240,480], except that the solution will be returned
* with the same normalization, i.e. lie within the
* interval specified.
*
* vstep const double
* Step size for solution search [deg]. If zero, a
* sensible, although perhaps non-optimal default will be
* used.
*
* viter int If a solution is not found then the step size will be
* halved and the search recommenced. viter controls how
* many times the step size is halved. The allowed range
* is 5 - 10.
*
* Given and returned:
* world double[naxis]
* World coordinate elements. world[wcs.lng] and
* world[wcs.lat] are the celestial longitude and
* latitude [deg]. Which is given and which returned
* depends on the value of mixcel. All other elements
* are given.
*
* Returned:
* phi,theta double[naxis]
* Longitude and latitude in the native coordinate
* system of the projection [deg].
*
* imgcrd double[naxis]
* Image coordinate elements. imgcrd[wcs.lng] and
* imgcrd[wcs.lat] are the projected x-, and
* y-coordinates in pseudo "degrees".
*
* Given and returned:
* pixcrd double[naxis]
* Pixel coordinate. The element indicated by mixpix is
* given and the remaining elements are returned.
*
* Function return value:
* int Status return value:
* 0: Success.
* 1: Null wcsprm pointer passed.
* 2: Memory allocation failed.
* 3: Linear transformation matrix is singular.
* 4: Inconsistent or unrecognized coordinate axis
* types.
* 5: Invalid parameter value.
* 6: Invalid coordinate transformation parameters.
* 7: Ill-conditioned coordinate transformation
* parameters.
* 10: Invalid world coordinate.
* 11: No solution found in the specified interval.
*
* For returns > 1, a detailed error message is set in
* wcsprm::err if enabled, see wcserr_enable().
*
* Notes:
* 1: Initially the specified solution interval is checked to see if it's a
* "crossing" interval. If it isn't, a search is made for a crossing
* solution by iterating on the unknown celestial coordinate starting at
* the upper limit of the solution interval and decrementing by the
* specified step size. A crossing is indicated if the trial value of the
* pixel coordinate steps through the value specified. If a crossing
* interval is found then the solution is determined by a modified form of
* "regula falsi" division of the crossing interval. If no crossing
* interval was found within the specified solution interval then a search
* is made for a "non-crossing" solution as may arise from a point of
* tangency. The process is complicated by having to make allowance for
* the discontinuities that occur in all map projections.
*
* Once one solution has been determined others may be found by subsequent
* invokations of wcsmix() with suitably restricted solution intervals.
*
* Note the circumstance that arises when the solution point lies at a
* native pole of a projection in which the pole is represented as a
* finite curve, for example the zenithals and conics. In such cases two
* or more valid solutions may exist but wcsmix() only ever returns one.
*
* Because of its generality wcsmix() is very compute-intensive. For
* compute-limited applications more efficient special-case solvers could
* be written for simple projections, for example non-oblique cylindrical
* projections.
*
*
* wcsccs() - Change celestial coordinate system
* ---------------------------------------------
* wcsccs() changes the celestial coordinate system of a wcsprm struct. For
* example, from equatorial to galactic coordinates.
*
* Parameters that define the spherical coordinate transformation, essentially
* being three Euler angles, must be provided. Thereby wcsccs() does not need
* prior knowledge of specific celestial coordinate systems. It also has the
* advantage of making it completely general.
*
* Auxiliary members of the wcsprm struct relating to equatorial celestial
* coordinate systems may also be changed.
*
* Only orthodox spherical coordinate systems are supported. That is, they
* must be right-handed, with latitude increasing from zero at the equator to
* +90 degrees at the pole. This precludes systems such as aziumuth and zenith
* distance, which, however, could be handled as negative azimuth and
* elevation.
*
* PLEASE NOTE: Information in the wcsprm struct relating to the original
* coordinate system will be overwritten and therefore lost. If this is
* undesirable, invoke wcsccs() on a copy of the struct made with wcssub().
* The wcsprm struct is reset on return with an explicit call to wcsset().
*
* Given and returned:
* wcs struct wcsprm*
* Coordinate transformation parameters. Particular
* "values to be given" elements of the wcsprm struct
* are modified.
*
* Given:
* lng2p1,
* lat2p1 double Longitude and latitude in the new celestial coordinate
* system of the pole (i.e. latitude +90) of the original
* system [deg]. See notes 1 and 2 below.
*
* lng1p2 double Longitude in the original celestial coordinate system
* of the pole (i.e. latitude +90) of the new system
* [deg]. See note 1 below.
*
* clng,clat const char*
* Longitude and latitude identifiers of the new CTYPEia
* celestial axis codes, without trailing dashes. For
* example, "RA" and "DEC" or "GLON" and "GLAT". Up to
* four characters are used, longer strings need not be
* null-terminated.
*
* radesys const char*
* Used when transforming to equatorial coordinates,
* identified by clng == "RA" and clat = "DEC". May be
* set to the null pointer to preserve the current value.
* Up to 71 characters are used, longer strings need not
* be null-terminated.
*
* If the new coordinate system is anything other than
* equatorial, then wcsprm::radesys will be cleared.
*
* equinox double Used when transforming to equatorial coordinates. May
* be set to zero to preserve the current value.
*
* If the new coordinate system is not equatorial, then
* wcsprm::equinox will be marked as undefined.
*
* alt const char*
* Character code for alternate coordinate descriptions
* (i.e. the 'a' in keyword names such as CTYPEia). This
* is blank for the primary coordinate description, or
* one of the 26 upper-case letters, A-Z. May be set to
* the null pointer, or null string if no change is
* required.
*
* Function return value:
* int Status return value:
* 0: Success.
* 1: Null wcsprm pointer passed.
* 12: Invalid subimage specification (no celestial
* axes).
*
* Notes:
* 1: Follows the prescription given in WCS Paper II, Sect. 2.7 for changing
* celestial coordinates.
*
* The implementation takes account of indeterminacies that arise in that
* prescription in the particular cases where one of the poles of the new
* system is at the fiducial point, or one of them is at the native pole.
*
* 2: If lat2p1 == +90, i.e. where the poles of the two coordinate systems
* coincide, then the spherical coordinate transformation becomes a simple
* change in origin of longitude given by
* lng2 = lng1 + (lng2p1 - lng1p2 - 180), and lat2 = lat1, where
* (lng2,lat2) are coordinates in the new system, and (lng1,lat1) are
* coordinates in the original system.
*
* Likewise, if lat2p1 == -90, then lng2 = -lng1 + (lng2p1 + lng1p2), and
* lat2 = -lat1.
*
* 3: For example, if the original coordinate system is B1950 equatorial and
* the desired new coordinate system is galactic, then
*
* - (lng2p1,lat2p1) are the galactic coordinates of the B1950 celestial
* pole, defined by the IAU to be (123.0,+27.4), and lng1p2 is the B1950
* right ascension of the galactic pole, defined as 192.25. Clearly
* these coordinates are fixed for a particular coordinate
* transformation.
*
* - (clng,clat) would be 'GLON' and 'GLAT', these being the FITS standard
* identifiers for galactic coordinates.
*
* - Since the new coordinate system is not equatorial, wcsprm::radesys
* and wcsprm::equinox will be cleared.
*
* 4. The coordinates required for some common transformations (obtained from
* https://ned.ipac.caltech.edu/coordinate_calculator) are as follows:
*
= (123.0000,+27.4000) galactic coordinates of B1950 celestial pole,
= (192.2500,+27.4000) B1950 equatorial coordinates of galactic pole.
*
= (122.9319,+27.1283) galactic coordinates of J2000 celestial pole,
= (192.8595,+27.1283) J2000 equatorial coordinates of galactic pole.
*
= (359.6774,+89.7217) B1950 equatorial coordinates of J2000 pole,
= (180.3162,+89.7217) J2000 equatorial coordinates of B1950 pole.
*
= (270.0000,+66.5542) B1950 equatorial coordinates of B1950 ecliptic pole,
= ( 90.0000,+66.5542) B1950 ecliptic coordinates of B1950 celestial pole.
*
= (270.0000,+66.5607) J2000 equatorial coordinates of J2000 ecliptic pole,
= ( 90.0000,+66.5607) J2000 ecliptic coordinates of J2000 celestial pole.
*
= ( 26.7315,+15.6441) supergalactic coordinates of B1950 celestial pole,
= (283.1894,+15.6441) B1950 equatorial coordinates of supergalactic pole.
*
= ( 26.4505,+15.7089) supergalactic coordinates of J2000 celestial pole,
= (283.7542,+15.7089) J2000 equatorial coordinates of supergalactic pole.
*
*
* wcssptr() - Spectral axis translation
* -------------------------------------
* wcssptr() translates the spectral axis in a wcsprm struct. For example, a
* 'FREQ' axis may be translated into 'ZOPT-F2W' and vice versa.
*
* PLEASE NOTE: Information in the wcsprm struct relating to the original
* coordinate system will be overwritten and therefore lost. If this is
* undesirable, invoke wcssptr() on a copy of the struct made with wcssub().
* The wcsprm struct is reset on return with an explicit call to wcsset().
*
* Given and returned:
* wcs struct wcsprm*
* Coordinate transformation parameters.
*
* i int* Index of the spectral axis (0-relative). If given < 0
* it will be set to the first spectral axis identified
* from the ctype[] keyvalues in the wcsprm struct.
*
* ctype char[9] Desired spectral CTYPEia. Wildcarding may be used as
* for the ctypeS2 argument to spctrn() as described in
* the prologue of spc.h, i.e. if the final three
* characters are specified as "???", or if just the
* eighth character is specified as '?', the correct
* algorithm code will be substituted and returned.
*
* Function return value:
* int Status return value:
* 0: Success.
* 1: Null wcsprm pointer passed.
* 2: Memory allocation failed.
* 3: Linear transformation matrix is singular.
* 4: Inconsistent or unrecognized coordinate axis
* types.
* 5: Invalid parameter value.
* 6: Invalid coordinate transformation parameters.
* 7: Ill-conditioned coordinate transformation
* parameters.
* 12: Invalid subimage specification (no spectral
* axis).
*
* For returns > 1, a detailed error message is set in
* wcsprm::err if enabled, see wcserr_enable().
*
*
* wcslib_version() - WCSLIB version number
* ----------------------------------------
* wcslib_version() returns the WCSLIB version number.
*
* The major version number changes when the ABI changes or when the license
* conditions change. ABI changes typically result from a change to the
* contents of one of the structs. The major version number is used to
* distinguish between incompatible versions of the sharable library.
*
* The minor version number changes with new functionality or bug fixes that do
* not involve a change in the ABI.
*
* The auxiliary version number (which is often absent) signals changes to the
* documentation, test suite, build procedures, or any other change that does
* not affect the compiled library.
*
* Returned:
* vers[3] int[3] The broken-down version number:
* 0: Major version number.
* 1: Minor version number.
* 2: Auxiliary version number (zero if absent).
* May be given as a null pointer if not required.
*
* Function return value:
* char* A null-terminated, statically allocated string
* containing the version number in the usual form, i.e.
* "<major>.<minor>.<auxiliary>".
*
*
* wcsprm struct - Coordinate transformation parameters
* ----------------------------------------------------
* The wcsprm struct contains information required to transform world
* coordinates. It consists of certain members that must be set by the user
* ("given") and others that are set by the WCSLIB routines ("returned").
* While the addresses of the arrays themselves may be set by wcsinit() if it
* (optionally) allocates memory, their contents must be set by the user.
*
* Some parameters that are given are not actually required for transforming
* coordinates. These are described as "auxiliary"; the struct simply provides
* a place to store them, though they may be used by wcshdo() in constructing a
* FITS header from a wcsprm struct. Some of the returned values are supplied
* for informational purposes and others are for internal use only as
* indicated.
*
* In practice, it is expected that a WCS parser would scan the FITS header to
* determine the number of coordinate axes. It would then use wcsinit() to
* allocate memory for arrays in the wcsprm struct and set default values.
* Then as it reread the header and identified each WCS keyrecord it would load
* the value into the relevant wcsprm array element. This is essentially what
* wcspih() does - refer to the prologue of wcshdr.h. As the final step,
* wcsset() is invoked, either directly or indirectly, to set the derived
* members of the wcsprm struct. wcsset() strips off trailing blanks in all
* string members and null-fills the character array.
*
* int flag
* (Given and returned) This flag must be set to zero (or 1, see wcsset())
* whenever any of the following wcsprm members are set or changed:
*
* - wcsprm::naxis (q.v., not normally set by the user),
* - wcsprm::crpix,
* - wcsprm::pc,
* - wcsprm::cdelt,
* - wcsprm::crval,
* - wcsprm::cunit,
* - wcsprm::ctype,
* - wcsprm::lonpole,
* - wcsprm::latpole,
* - wcsprm::restfrq,
* - wcsprm::restwav,
* - wcsprm::npv,
* - wcsprm::pv,
* - wcsprm::nps,
* - wcsprm::ps,
* - wcsprm::cd,
* - wcsprm::crota,
* - wcsprm::altlin,
* - wcsprm::ntab,
* - wcsprm::nwtb,
* - wcsprm::tab,
* - wcsprm::wtb.
*
* This signals the initialization routine, wcsset(), to recompute the
* returned members of the linprm, celprm, spcprm, and tabprm structs.
* wcsset() will reset flag to indicate that this has been done.
*
* PLEASE NOTE: flag should be set to -1 when wcsinit() is called for the
* first time for a particular wcsprm struct in order to initialize memory
* management. It must ONLY be used on the first initialization otherwise
* memory leaks may result.
*
* int naxis
* (Given or returned) Number of pixel and world coordinate elements.
*
* If wcsinit() is used to initialize the linprm struct (as would normally
* be the case) then it will set naxis from the value passed to it as a
* function argument. The user should not subsequently modify it.
*
* double *crpix
* (Given) Address of the first element of an array of double containing
* the coordinate reference pixel, CRPIXja.
*
* double *pc
* (Given) Address of the first element of the PCi_ja (pixel coordinate)
* transformation matrix. The expected order is
*
= struct wcsprm wcs;
= wcs.pc = {PC1_1, PC1_2, PC2_1, PC2_2};
*
* This may be constructed conveniently from a 2-D array via
*
= double m[2][2] = {{PC1_1, PC1_2},
= {PC2_1, PC2_2}};
*
* which is equivalent to
*
= double m[2][2];
= m[0][0] = PC1_1;
= m[0][1] = PC1_2;
= m[1][0] = PC2_1;
= m[1][1] = PC2_2;
*
* The storage order for this 2-D array is the same as for the 1-D array,
* whence
*
= wcs.pc = *m;
*
* would be legitimate.
*
* double *cdelt
* (Given) Address of the first element of an array of double containing
* the coordinate increments, CDELTia.
*
* double *crval
* (Given) Address of the first element of an array of double containing
* the coordinate reference values, CRVALia.
*
* char (*cunit)[72]
* (Given) Address of the first element of an array of char[72] containing
* the CUNITia keyvalues which define the units of measurement of the
* CRVALia, CDELTia, and CDi_ja keywords.
*
* As CUNITia is an optional header keyword, cunit[][72] may be left blank
* but otherwise is expected to contain a standard units specification as
* defined by WCS Paper I. Utility function wcsutrn(), described in
* wcsunits.h, is available to translate commonly used non-standard units
* specifications but this must be done as a separate step before invoking
* wcsset().
*
* For celestial axes, if cunit[][72] is not blank, wcsset() uses
* wcsunits() to parse it and scale cdelt[], crval[], and cd[][*] to
* degrees. It then resets cunit[][72] to "deg".
*
* For spectral axes, if cunit[][72] is not blank, wcsset() uses wcsunits()
* to parse it and scale cdelt[], crval[], and cd[][*] to SI units. It
* then resets cunit[][72] accordingly.
*
* wcsset() ignores cunit[][72] for other coordinate types; cunit[][72] may
* be used to label coordinate values.
*
* These variables accomodate the longest allowed string-valued FITS
* keyword, being limited to 68 characters, plus the null-terminating
* character.
*
* char (*ctype)[72]
* (Given) Address of the first element of an array of char[72] containing
* the coordinate axis types, CTYPEia.
*
* The ctype[][72] keyword values must be in upper case and there must be
* zero or one pair of matched celestial axis types, and zero or one
* spectral axis. The ctype[][72] strings should be padded with blanks on
* the right and null-terminated so that they are at least eight characters
* in length.
*
* These variables accomodate the longest allowed string-valued FITS
* keyword, being limited to 68 characters, plus the null-terminating
* character.
*
* double lonpole
* (Given and returned) The native longitude of the celestial pole, phi_p,
* given by LONPOLEa [deg] or by PVi_2a [deg] attached to the longitude
* axis which takes precedence if defined, and ...
* double latpole
* (Given and returned) ... the native latitude of the celestial pole,
* theta_p, given by LATPOLEa [deg] or by PVi_3a [deg] attached to the
* longitude axis which takes precedence if defined.
*
* lonpole and latpole may be left to default to values set by wcsinit()
* (see celprm::ref), but in any case they will be reset by wcsset() to
* the values actually used. Note therefore that if the wcsprm struct is
* reused without resetting them, whether directly or via wcsinit(), they
* will no longer have their default values.
*
* double restfrq
* (Given) The rest frequency [Hz], and/or ...
* double restwav
* (Given) ... the rest wavelength in vacuo [m], only one of which need be
* given, the other should be set to zero.
*
* int npv
* (Given) The number of entries in the wcsprm::pv[] array.
*
* int npvmax
* (Given or returned) The length of the wcsprm::pv[] array.
*
* npvmax will be set by wcsinit() if it allocates memory for wcsprm::pv[],
* otherwise it must be set by the user. See also wcsnpv().
*
* struct pvcard *pv
* (Given) Address of the first element of an array of length npvmax of
* pvcard structs.
*
* As a FITS header parser encounters each PVi_ma keyword it should load it
* into a pvcard struct in the array and increment npv. wcsset()
* interprets these as required.
*
* Note that, if they were not given, wcsset() resets the entries for
* PVi_1a, PVi_2a, PVi_3a, and PVi_4a for longitude axis i to match
* phi_0 and theta_0 (the native longitude and latitude of the reference
* point), LONPOLEa and LATPOLEa respectively.
*
* int nps
* (Given) The number of entries in the wcsprm::ps[] array.
*
* int npsmax
* (Given or returned) The length of the wcsprm::ps[] array.
*
* npsmax will be set by wcsinit() if it allocates memory for wcsprm::ps[],
* otherwise it must be set by the user. See also wcsnps().
*
* struct pscard *ps
* (Given) Address of the first element of an array of length npsmax of
* pscard structs.
*
* As a FITS header parser encounters each PSi_ma keyword it should load it
* into a pscard struct in the array and increment nps. wcsset()
* interprets these as required (currently no PSi_ma keyvalues are
* recognized).
*
* double *cd
* (Given) For historical compatibility, the wcsprm struct supports two
* alternate specifications of the linear transformation matrix, those
* associated with the CDi_ja keywords, and ...
* double *crota
* (Given) ... those associated with the CROTAi keywords. Although these
* may not formally co-exist with PCi_ja, the approach taken here is simply
* to ignore them if given in conjunction with PCi_ja.
*
* int altlin
* (Given) altlin is a bit flag that denotes which of the PCi_ja, CDi_ja
* and CROTAi keywords are present in the header:
*
* - Bit 0: PCi_ja is present.
*
* - Bit 1: CDi_ja is present.
*
* Matrix elements in the IRAF convention are equivalent to the product
* CDi_ja = CDELTia * PCi_ja, but the defaults differ from that of the
* PCi_ja matrix. If one or more CDi_ja keywords are present then all
* unspecified CDi_ja default to zero. If no CDi_ja (or CROTAi) keywords
* are present, then the header is assumed to be in PCi_ja form whether
* or not any PCi_ja keywords are present since this results in an
* interpretation of CDELTia consistent with the original FITS
* specification.
*
* While CDi_ja may not formally co-exist with PCi_ja, it may co-exist
* with CDELTia and CROTAi which are to be ignored.
*
* - Bit 2: CROTAi is present.
*
* In the AIPS convention, CROTAi may only be associated with the
* latitude axis of a celestial axis pair. It specifies a rotation in
* the image plane that is applied AFTER the CDELTia; any other CROTAi
* keywords are ignored.
*
* CROTAi may not formally co-exist with PCi_ja.
*
* CROTAi and CDELTia may formally co-exist with CDi_ja but if so are to
* be ignored.
*
* - Bit 3: PCi_ja + CDELTia was derived from CDi_ja by wcspcx().
*
* This bit is set by wcspcx() when it derives PCi_ja and CDELTia from
* CDi_ja via an orthonormal decomposition. In particular, it signals
* wcsset() not to replace PCi_ja by a copy of CDi_ja with CDELTia set
* to unity.
*
* CDi_ja and CROTAi keywords, if found, are to be stored in the wcsprm::cd
* and wcsprm::crota arrays which are dimensioned similarly to wcsprm::pc
* and wcsprm::cdelt. FITS header parsers should use the following
* procedure:
*
* - Whenever a PCi_ja keyword is encountered: altlin |= 1;
*
* - Whenever a CDi_ja keyword is encountered: altlin |= 2;
*
* - Whenever a CROTAi keyword is encountered: altlin |= 4;
*
* If none of these bits are set the PCi_ja representation results, i.e.
* wcsprm::pc and wcsprm::cdelt will be used as given.
*
* These alternate specifications of the linear transformation matrix are
* translated immediately to PCi_ja by wcsset() and are invisible to the
* lower-level WCSLIB routines. In particular, unless bit 3 is also set,
* wcsset() resets wcsprm::cdelt to unity if CDi_ja is present (and no
* PCi_ja).
*
* If CROTAi are present but none is associated with the latitude axis
* (and no PCi_ja or CDi_ja), then wcsset() reverts to a unity PCi_ja
* matrix.
*
* int velref
* (Given) AIPS velocity code VELREF, refer to spcaips().
*
* It is not necessary to reset the wcsprm struct (via wcsset()) when
* wcsprm::velref is changed.
*
* char alt[4]
* (Given, auxiliary) Character code for alternate coordinate descriptions
* (i.e. the 'a' in keyword names such as CTYPEia). This is blank for the
* primary coordinate description, or one of the 26 upper-case letters,
* A-Z.
*
* An array of four characters is provided for alignment purposes, only the
* first is used.
*
* It is not necessary to reset the wcsprm struct (via wcsset()) when
* wcsprm::alt is changed.
*
* int colnum
* (Given, auxiliary) Where the coordinate representation is associated
* with an image-array column in a FITS binary table, this variable may be
* used to record the relevant column number.
*
* It should be set to zero for an image header or pixel list.
*
* It is not necessary to reset the wcsprm struct (via wcsset()) when
* wcsprm::colnum is changed.
*
* int *colax
* (Given, auxiliary) Address of the first element of an array of int
* recording the column numbers for each axis in a pixel list.
*
* The array elements should be set to zero for an image header or image
* array in a binary table.
*
* It is not necessary to reset the wcsprm struct (via wcsset()) when
* wcsprm::colax is changed.
*
* char (*cname)[72]
* (Given, auxiliary) The address of the first element of an array of
* char[72] containing the coordinate axis names, CNAMEia.
*
* These variables accomodate the longest allowed string-valued FITS
* keyword, being limited to 68 characters, plus the null-terminating
* character.
*
* It is not necessary to reset the wcsprm struct (via wcsset()) when
* wcsprm::cname is changed.
*
* double *crder
* (Given, auxiliary) Address of the first element of an array of double
* recording the random error in the coordinate value, CRDERia.
*
* It is not necessary to reset the wcsprm struct (via wcsset()) when
* wcsprm::crder is changed.
*
* double *csyer
* (Given, auxiliary) Address of the first element of an array of double
* recording the systematic error in the coordinate value, CSYERia.
*
* It is not necessary to reset the wcsprm struct (via wcsset()) when
* wcsprm::csyer is changed.
*
* double *czphs
* (Given, auxiliary) Address of the first element of an array of double
* recording the time at the zero point of a phase axis, CZPHSia.
*
* It is not necessary to reset the wcsprm struct (via wcsset()) when
* wcsprm::czphs is changed.
*
* double *cperi
* (Given, auxiliary) Address of the first element of an array of double
* recording the period of a phase axis, CPERIia.
*
* It is not necessary to reset the wcsprm struct (via wcsset()) when
* wcsprm::cperi is changed.
*
* char wcsname[72]
* (Given, auxiliary) The name given to the coordinate representation,
* WCSNAMEa. This variable accomodates the longest allowed string-valued
* FITS keyword, being limited to 68 characters, plus the null-terminating
* character.
*
* It is not necessary to reset the wcsprm struct (via wcsset()) when
* wcsprm::wcsname is changed.
*
* char timesys[72]
* (Given, auxiliary) TIMESYS keyvalue, being the time scale (UTC, TAI,
* etc.) in which all other time-related auxiliary header values are
* recorded. Also defines the time scale for an image axis with CTYPEia
* set to 'TIME'.
*
* It is not necessary to reset the wcsprm struct (via wcsset()) when
* wcsprm::timesys is changed.
*
* char trefpos[72]
* (Given, auxiliary) TREFPOS keyvalue, being the location in space where
* the recorded time is valid.
*
* It is not necessary to reset the wcsprm struct (via wcsset()) when
* wcsprm::trefpos is changed.
*
* char trefdir[72]
* (Given, auxiliary) TREFDIR keyvalue, being the reference direction used
* in calculating a pathlength delay.
*
* It is not necessary to reset the wcsprm struct (via wcsset()) when
* wcsprm::trefdir is changed.
*
* char plephem[72]
* (Given, auxiliary) PLEPHEM keyvalue, being the Solar System ephemeris
* used for calculating a pathlength delay.
*
* It is not necessary to reset the wcsprm struct (via wcsset()) when
* wcsprm::plephem is changed.
*
* char timeunit[72]
* (Given, auxiliary) TIMEUNIT keyvalue, being the time units in which
* the following header values are expressed: TSTART, TSTOP, TIMEOFFS,
* TIMSYER, TIMRDER, TIMEDEL. It also provides the default value for
* CUNITia for time axes.
*
* It is not necessary to reset the wcsprm struct (via wcsset()) when
* wcsprm::timeunit is changed.
*
* char dateref[72]
* (Given, auxiliary) DATEREF keyvalue, being the date of a reference epoch
* relative to which other time measurements refer.
*
* It is not necessary to reset the wcsprm struct (via wcsset()) when
* wcsprm::dateref is changed.
*
* double mjdref[2]
* (Given, auxiliary) MJDREF keyvalue, equivalent to DATEREF expressed as
* a Modified Julian Date (MJD = JD - 2400000.5). The value is given as
* the sum of the two-element vector, allowing increased precision.
*
* It is not necessary to reset the wcsprm struct (via wcsset()) when
* wcsprm::mjdref is changed.
*
* double timeoffs
* (Given, auxiliary) TIMEOFFS keyvalue, being a time offset, which may be
* used, for example, to provide a uniform clock correction for times
* referenced to DATEREF.
*
* It is not necessary to reset the wcsprm struct (via wcsset()) when
* wcsprm::timeoffs is changed.
*
* char dateobs[72]
* (Given, auxiliary) DATE-OBS keyvalue, being the date at the start of the
* observation unless otherwise explained in the DATE-OBS keycomment, in
* ISO format, yyyy-mm-ddThh:mm:ss.
*
* It is not necessary to reset the wcsprm struct (via wcsset()) when
* wcsprm::dateobs is changed.
*
* char datebeg[72]
* (Given, auxiliary) DATE-BEG keyvalue, being the date at the start of the
* observation in ISO format, yyyy-mm-ddThh:mm:ss.
*
* It is not necessary to reset the wcsprm struct (via wcsset()) when
* wcsprm::datebeg is changed.
*
* char dateavg[72]
* (Given, auxiliary) DATE-AVG keyvalue, being the date at a representative
* mid-point of the observation in ISO format, yyyy-mm-ddThh:mm:ss.
*
* It is not necessary to reset the wcsprm struct (via wcsset()) when
* wcsprm::dateavg is changed.
*
* char dateend[72]
* (Given, auxiliary) DATE-END keyvalue, baing the date at the end of the
* observation in ISO format, yyyy-mm-ddThh:mm:ss.
*
* It is not necessary to reset the wcsprm struct (via wcsset()) when
* wcsprm::dateend is changed.
*
* double mjdobs
* (Given, auxiliary) MJD-OBS keyvalue, equivalent to DATE-OBS expressed
* as a Modified Julian Date (MJD = JD - 2400000.5).
*
* It is not necessary to reset the wcsprm struct (via wcsset()) when
* wcsprm::mjdobs is changed.
*
* double mjdbeg
* (Given, auxiliary) MJD-BEG keyvalue, equivalent to DATE-BEG expressed
* as a Modified Julian Date (MJD = JD - 2400000.5).
*
* It is not necessary to reset the wcsprm struct (via wcsset()) when
* wcsprm::mjdbeg is changed.
*
* double mjdavg
* (Given, auxiliary) MJD-AVG keyvalue, equivalent to DATE-AVG expressed
* as a Modified Julian Date (MJD = JD - 2400000.5).
*
* It is not necessary to reset the wcsprm struct (via wcsset()) when
* wcsprm::mjdavg is changed.
*
* double mjdend
* (Given, auxiliary) MJD-END keyvalue, equivalent to DATE-END expressed
* as a Modified Julian Date (MJD = JD - 2400000.5).
*
* It is not necessary to reset the wcsprm struct (via wcsset()) when
* wcsprm::mjdend is changed.
*
* double jepoch
* (Given, auxiliary) JEPOCH keyvalue, equivalent to DATE-OBS expressed
* as a Julian epoch.
*
* It is not necessary to reset the wcsprm struct (via wcsset()) when
* wcsprm::jepoch is changed.
*
* double bepoch
* (Given, auxiliary) BEPOCH keyvalue, equivalent to DATE-OBS expressed
* as a Besselian epoch
*
* It is not necessary to reset the wcsprm struct (via wcsset()) when
* wcsprm::bepoch is changed.
*
* double tstart
* (Given, auxiliary) TSTART keyvalue, equivalent to DATE-BEG expressed
* as a time in units of TIMEUNIT relative to DATEREF+TIMEOFFS.
*
* It is not necessary to reset the wcsprm struct (via wcsset()) when
* wcsprm::tstart is changed.
*
* double tstop
* (Given, auxiliary) TSTOP keyvalue, equivalent to DATE-END expressed
* as a time in units of TIMEUNIT relative to DATEREF+TIMEOFFS.
*
* It is not necessary to reset the wcsprm struct (via wcsset()) when
* wcsprm::tstop is changed.
*
* double xposure
* (Given, auxiliary) XPOSURE keyvalue, being the effective exposure time
* in units of TIMEUNIT.
*
* It is not necessary to reset the wcsprm struct (via wcsset()) when
* wcsprm::xposure is changed.
*
* double telapse
* (Given, auxiliary) TELAPSE keyvalue, equivalent to the elapsed time
* between DATE-BEG and DATE-END, in units of TIMEUNIT.
*
* It is not necessary to reset the wcsprm struct (via wcsset()) when
* wcsprm::telapse is changed.
*
* double timsyer
* (Given, auxiliary) TIMSYER keyvalue, being the absolute error of the
* time values, in units of TIMEUNIT.
*
* It is not necessary to reset the wcsprm struct (via wcsset()) when
* wcsprm::timsyer is changed.
*
* double timrder
* (Given, auxiliary) TIMRDER keyvalue, being the accuracy of time stamps
* relative to each other, in units of TIMEUNIT.
*
* It is not necessary to reset the wcsprm struct (via wcsset()) when
* wcsprm::timrder is changed.
*
* double timedel
* (Given, auxiliary) TIMEDEL keyvalue, being the resolution of the time
* stamps.
*
* It is not necessary to reset the wcsprm struct (via wcsset()) when
* wcsprm::timedel is changed.
*
* double timepixr
* (Given, auxiliary) TIMEPIXR keyvalue, being the relative position of the
* time stamps in binned time intervals, a value between 0.0 and 1.0.
*
* It is not necessary to reset the wcsprm struct (via wcsset()) when
* wcsprm::timepixr is changed.
*
* double obsgeo[6]
* (Given, auxiliary) Location of the observer in a standard terrestrial
* reference frame. The first three give ITRS Cartesian coordinates
* OBSGEO-X [m], OBSGEO-Y [m], OBSGEO-Z [m], and the second three give
* OBSGEO-L [deg], OBSGEO-B [deg], OBSGEO-H [m], which are related through
* a standard transformation.
*
* It is not necessary to reset the wcsprm struct (via wcsset()) when
* wcsprm::obsgeo is changed.
*
* char obsorbit[72]
* (Given, auxiliary) OBSORBIT keyvalue, being the URI, URL, or name of an
* orbit ephemeris file giving spacecraft coordinates relating to TREFPOS.
*
* It is not necessary to reset the wcsprm struct (via wcsset()) when
* wcsprm::obsorbit is changed.
*
* char radesys[72]
* (Given, auxiliary) The equatorial or ecliptic coordinate system type,
* RADESYSa.
*
* It is not necessary to reset the wcsprm struct (via wcsset()) when
* wcsprm::radesys is changed.
*
* double equinox
* (Given, auxiliary) The equinox associated with dynamical equatorial or
* ecliptic coordinate systems, EQUINOXa (or EPOCH in older headers). Not
* applicable to ICRS equatorial or ecliptic coordinates.
*
* It is not necessary to reset the wcsprm struct (via wcsset()) when
* wcsprm::equinox is changed.
*
* char specsys[72]
* (Given, auxiliary) Spectral reference frame (standard of rest),
* SPECSYSa.
*
* It is not necessary to reset the wcsprm struct (via wcsset()) when
* wcsprm::specsys is changed.
*
* char ssysobs[72]
* (Given, auxiliary) The spectral reference frame in which there is no
* differential variation in the spectral coordinate across the
* field-of-view, SSYSOBSa.
*
* It is not necessary to reset the wcsprm struct (via wcsset()) when
* wcsprm::ssysobs is changed.
*
* double velosys
* (Given, auxiliary) The relative radial velocity [m/s] between the
* observer and the selected standard of rest in the direction of the
* celestial reference coordinate, VELOSYSa.
*
* It is not necessary to reset the wcsprm struct (via wcsset()) when
* wcsprm::velosys is changed.
*
* double zsource
* (Given, auxiliary) The redshift, ZSOURCEa, of the source.
*
* It is not necessary to reset the wcsprm struct (via wcsset()) when
* wcsprm::zsource is changed.
*
* char ssyssrc[72]
* (Given, auxiliary) The spectral reference frame (standard of rest),
* SSYSSRCa, in which wcsprm::zsource was measured.
*
* It is not necessary to reset the wcsprm struct (via wcsset()) when
* wcsprm::ssyssrc is changed.
*
* double velangl
* (Given, auxiliary) The angle [deg] that should be used to decompose an
* observed velocity into radial and transverse components.
*
* It is not necessary to reset the wcsprm struct (via wcsset()) when
* wcsprm::velangl is changed.
*
* struct auxprm *aux
* (Given, auxiliary) This struct holds auxiliary coordinate system
* information of a specialist nature. While these parameters may be
* widely recognized within particular fields of astronomy, they differ
* from the above auxiliary parameters in not being defined by any of the
* FITS WCS standards. Collecting them together in a separate struct that
* is allocated only when required helps to control bloat in the size of
* the wcsprm struct.
*
* int ntab
* (Given) See wcsprm::tab.
*
* int nwtb
* (Given) See wcsprm::wtb.
*
* struct tabprm *tab
* (Given) Address of the first element of an array of ntab tabprm structs
* for which memory has been allocated. These are used to store tabular
* transformation parameters.
*
* Although technically wcsprm::ntab and tab are "given", they will
* normally be set by invoking wcstab(), whether directly or indirectly.
*
* The tabprm structs contain some members that must be supplied and others
* that are derived. The information to be supplied comes primarily from
* arrays stored in one or more FITS binary table extensions. These
* arrays, referred to here as "wcstab arrays", are themselves located by
* parameters stored in the FITS image header.
*
* struct wtbarr *wtb
* (Given) Address of the first element of an array of nwtb wtbarr structs
* for which memory has been allocated. These are used in extracting
* wcstab arrays from a FITS binary table.
*
* Although technically wcsprm::nwtb and wtb are "given", they will
* normally be set by invoking wcstab(), whether directly or indirectly.
*
* char lngtyp[8]
* (Returned) Four-character WCS celestial longitude and ...
* char lattyp[8]
* (Returned) ... latitude axis types. e.g. "RA", "DEC", "GLON", "GLAT",
* etc. extracted from 'RA--', 'DEC-', 'GLON', 'GLAT', etc. in the first
* four characters of CTYPEia but with trailing dashes removed. (Declared
* as char[8] for alignment reasons.)
*
* int lng
* (Returned) Index for the longitude coordinate, and ...
* int lat
* (Returned) ... index for the latitude coordinate, and ...
* int spec
* (Returned) ... index for the spectral coordinate, and ...
* int time
* (Returned) ... index for the time coordinate in the imgcrd[][] and
* world[][] arrays in the API of wcsp2s(), wcss2p() and wcsmix().
*
* These may also serve as indices into the pixcrd[][] array provided that
* the PCi_ja matrix does not transpose axes.
*
* int cubeface
* (Returned) Index into the pixcrd[][] array for the CUBEFACE axis. This
* is used for quadcube projections where the cube faces are stored on a
* separate axis (see wcs.h).
*
* int chksum
* (Returned) Checksum of keyvalues provided (see wcsprm::flag). Used by
* wcsenq() to validate the self-consistency of the struct. Note that
* the checksum incorporates addresses and is therefore highly specific to
* the instance of the wcsprm struct.
*
* int *types
* (Returned) Address of the first element of an array of int containing a
* four-digit type code for each axis.
*
* - First digit (i.e. 1000s):
* - 0: Non-specific coordinate type.
* - 1: Stokes coordinate.
* - 2: Celestial coordinate (including CUBEFACE).
* - 3: Spectral coordinate.
* - 4: Time coordinate.
*
* - Second digit (i.e. 100s):
* - 0: Linear axis.
* - 1: Quantized axis (STOKES, CUBEFACE).
* - 2: Non-linear celestial axis.
* - 3: Non-linear spectral axis.
* - 4: Logarithmic axis.
* - 5: Tabular axis.
*
* - Third digit (i.e. 10s):
* - 0: Group number, e.g. lookup table number, being an index into the
* tabprm array (see above).
*
* - The fourth digit is used as a qualifier depending on the axis type.
*
* - For celestial axes:
* - 0: Longitude coordinate.
* - 1: Latitude coordinate.
* - 2: CUBEFACE number.
*
* - For lookup tables: the axis number in a multidimensional table.
*
* CTYPEia in "4-3" form with unrecognized algorithm code will have its
* type set to -1 and generate an error.
*
* struct linprm lin
* (Returned) Linear transformation parameters (usage is described in the
* prologue to lin.h).
*
* struct celprm cel
* (Returned) Celestial transformation parameters (usage is described in
* the prologue to cel.h).
*
* struct spcprm spc
* (Returned) Spectral transformation parameters (usage is described in the
* prologue to spc.h).
*
* struct wcserr *err
* (Returned) If enabled, when an error status is returned, this struct
* contains detailed information about the error, see wcserr_enable().
*
* int m_flag
* (For internal use only.)
* int m_naxis
* (For internal use only.)
* double *m_crpix
* (For internal use only.)
* double *m_pc
* (For internal use only.)
* double *m_cdelt
* (For internal use only.)
* double *m_crval
* (For internal use only.)
* char (*m_cunit)[72]
* (For internal use only.)
* char (*m_ctype)[72]
* (For internal use only.)
* struct pvcard *m_pv
* (For internal use only.)
* struct pscard *m_ps
* (For internal use only.)
* double *m_cd
* (For internal use only.)
* double *m_crota
* (For internal use only.)
* int *m_colax
* (For internal use only.)
* char (*m_cname)[72]
* (For internal use only.)
* double *m_crder
* (For internal use only.)
* double *m_csyer
* (For internal use only.)
* double *m_czphs
* (For internal use only.)
* double *m_cperi
* (For internal use only.)
* struct tabprm *m_tab
* (For internal use only.)
* struct wtbarr *m_wtb
* (For internal use only.)
*
*
* pvcard struct - Store for PVi_ma keyrecords
* -------------------------------------------
* The pvcard struct is used to pass the parsed contents of PVi_ma keyrecords
* to wcsset() via the wcsprm struct.
*
* All members of this struct are to be set by the user.
*
* int i
* (Given) Axis number (1-relative), as in the FITS PVi_ma keyword. If
* i == 0, wcsset() will replace it with the latitude axis number.
*
* int m
* (Given) Parameter number (non-negative), as in the FITS PVi_ma keyword.
*
* double value
* (Given) Parameter value.
*
*
* pscard struct - Store for PSi_ma keyrecords
* -------------------------------------------
* The pscard struct is used to pass the parsed contents of PSi_ma keyrecords
* to wcsset() via the wcsprm struct.
*
* All members of this struct are to be set by the user.
*
* int i
* (Given) Axis number (1-relative), as in the FITS PSi_ma keyword.
*
* int m
* (Given) Parameter number (non-negative), as in the FITS PSi_ma keyword.
*
* char value[72]
* (Given) Parameter value.
*
*
* auxprm struct - Additional auxiliary parameters
* -----------------------------------------------
* The auxprm struct holds auxiliary coordinate system information of a
* specialist nature. It is anticipated that this struct will expand in future
* to accomodate additional parameters.
*
* All members of this struct are to be set by the user.
*
* double rsun_ref
* (Given, auxiliary) Reference radius of the Sun used in coordinate
* calculations (m).
*
* double dsun_obs
* (Given, auxiliary) Distance between the centre of the Sun and the
* observer (m).
*
* double crln_obs
* (Given, auxiliary) Carrington heliographic longitude of the observer
* (deg).
*
* double hgln_obs
* (Given, auxiliary) Stonyhurst heliographic longitude of the observer
* (deg).
*
* double hglt_obs
* (Given, auxiliary) Heliographic latitude (Carrington or Stonyhurst) of
* the observer (deg).
*
* double a_radius
* Length of the semi-major axis of a triaxial ellipsoid approximating the
* shape of a body (e.g. planet) in the solar system (m).
*
* double b_radius
* Length of the intermediate axis, normal to the semi-major and semi-minor
* axes, of a triaxial ellipsoid approximating the shape of a body (m).
*
* double c_radius
* Length of the semi-minor axis, normal to the semi-major axis, of a
* triaxial ellipsoid approximating the shape of a body (m).
*
* double blon_obs
* Bodycentric longitude of the observer in the coordinate system fixed to
* the planet or other solar system body (deg, in range 0 to 360).
*
* double blat_obs
* Bodycentric latitude of the observer in the coordinate system fixed to
* the planet or other solar system body (deg).
*
* double bdis_obs
* Bodycentric distance of the observer (m).
*
*
* Global variable: const char *wcs_errmsg[] - Status return messages
* ------------------------------------------------------------------
* Error messages to match the status value returned from each function.
*
*===========================================================================*/
#ifndef WCSLIB_WCS
#define WCSLIB_WCS
#include "lin.h"
#include "cel.h"
#include "spc.h"
#ifdef __cplusplus
extern "C" {
#define wtbarr wtbarr_s // See prologue of wtbarr.h.
#endif
enum wcsenq_enum {
WCSENQ_MEM = 1, // wcsprm struct memory is managed by WCSLIB.
WCSENQ_SET = 2, // wcsprm struct has been set up.
WCSENQ_BYP = 4, // wcsprm struct is in bypass mode.
WCSENQ_CHK = 8, // wcsprm struct is self-consistent.
};
#define WCSSUB_LONGITUDE 0x1001
#define WCSSUB_LATITUDE 0x1002
#define WCSSUB_CUBEFACE 0x1004
#define WCSSUB_CELESTIAL 0x1007
#define WCSSUB_SPECTRAL 0x1008
#define WCSSUB_STOKES 0x1010
#define WCSSUB_TIME 0x1020
#define WCSCOMPARE_ANCILLARY 0x0001
#define WCSCOMPARE_TILING 0x0002
#define WCSCOMPARE_CRPIX 0x0004
extern const char *wcs_errmsg[];
enum wcs_errmsg_enum {
WCSERR_SUCCESS = 0, // Success.
WCSERR_NULL_POINTER = 1, // Null wcsprm pointer passed.
WCSERR_MEMORY = 2, // Memory allocation failed.
WCSERR_SINGULAR_MTX = 3, // Linear transformation matrix is singular.
WCSERR_BAD_CTYPE = 4, // Inconsistent or unrecognized coordinate
// axis type.
WCSERR_BAD_PARAM = 5, // Invalid parameter value.
WCSERR_BAD_COORD_TRANS = 6, // Unrecognized coordinate transformation
// parameter.
WCSERR_ILL_COORD_TRANS = 7, // Ill-conditioned coordinate transformation
// parameter.
WCSERR_BAD_PIX = 8, // One or more of the pixel coordinates were
// invalid.
WCSERR_BAD_WORLD = 9, // One or more of the world coordinates were
// invalid.
WCSERR_BAD_WORLD_COORD = 10, // Invalid world coordinate.
WCSERR_NO_SOLUTION = 11, // No solution found in the specified
// interval.
WCSERR_BAD_SUBIMAGE = 12, // Invalid subimage specification.
WCSERR_NON_SEPARABLE = 13, // Non-separable subimage coordinate system.
WCSERR_UNSET = 14 // wcsprm struct is unset.
};
// Struct used for storing PVi_ma keywords.
struct pvcard {
int i; // Axis number, as in PVi_ma (1-relative).
int m; // Parameter number, ditto (0-relative).
double value; // Parameter value.
};
// Size of the pvcard struct in int units, used by the Fortran wrappers.
#define PVLEN (sizeof(struct pvcard)/sizeof(int))
// Struct used for storing PSi_ma keywords.
struct pscard {
int i; // Axis number, as in PSi_ma (1-relative).
int m; // Parameter number, ditto (0-relative).
char value[72]; // Parameter value.
};
// Size of the pscard struct in int units, used by the Fortran wrappers.
#define PSLEN (sizeof(struct pscard)/sizeof(int))
// Struct used to hold additional auxiliary parameters.
struct auxprm {
double rsun_ref; // Solar radius.
double dsun_obs; // Distance from Sun centre to observer.
double crln_obs; // Carrington heliographic lng of observer.
double hgln_obs; // Stonyhurst heliographic lng of observer.
double hglt_obs; // Heliographic latitude of observer.
double a_radius; // Semi-major axis of solar system body.
double b_radius; // Semi-intermediate axis of solar system body.
double c_radius; // Semi-minor axis of solar system body.
double blon_obs; // Bodycentric longitude of observer.
double blat_obs; // Bodycentric latitude of observer.
double bdis_obs; // Bodycentric distance of observer.
double dummy[2]; // Reserved for future use.
};
// Size of the auxprm struct in int units, used by the Fortran wrappers.
#define AUXLEN (sizeof(struct auxprm)/sizeof(int))
struct wcsprm {
// Initialization flag (see the prologue above).
//--------------------------------------------------------------------------
int flag; // Set to zero to force initialization.
// FITS header keyvalues to be provided (see the prologue above).
//--------------------------------------------------------------------------
int naxis; // Number of axes (pixel and coordinate).
double *crpix; // CRPIXja keyvalues for each pixel axis.
double *pc; // PCi_ja linear transformation matrix.
double *cdelt; // CDELTia keyvalues for each coord axis.
double *crval; // CRVALia keyvalues for each coord axis.
char (*cunit)[72]; // CUNITia keyvalues for each coord axis.
char (*ctype)[72]; // CTYPEia keyvalues for each coord axis.
double lonpole; // LONPOLEa keyvalue.
double latpole; // LATPOLEa keyvalue.
double restfrq; // RESTFRQa keyvalue.
double restwav; // RESTWAVa keyvalue.
int npv; // Number of PVi_ma keywords, and the
int npvmax; // number for which space was allocated.
struct pvcard *pv; // PVi_ma keywords for each i and m.
int nps; // Number of PSi_ma keywords, and the
int npsmax; // number for which space was allocated.
struct pscard *ps; // PSi_ma keywords for each i and m.
// Alternative header keyvalues (see the prologue above).
//--------------------------------------------------------------------------
double *cd; // CDi_ja linear transformation matrix.
double *crota; // CROTAi keyvalues for each coord axis.
int altlin; // Alternative representations
// Bit 0: PCi_ja is present,
// Bit 1: CDi_ja is present,
// Bit 2: CROTAi is present.
int velref; // AIPS velocity code, VELREF.
// Auxiliary coordinate system information of a general nature. Not
// used by WCSLIB. Refer to the prologue comments above for a brief
// explanation of these values.
char alt[4];
int colnum;
int *colax;
// Auxiliary coordinate axis information.
char (*cname)[72];
double *crder;
double *csyer;
double *czphs;
double *cperi;
char wcsname[72];
// Time reference system and measurement.
char timesys[72], trefpos[72], trefdir[72], plephem[72];
char timeunit[72];
char dateref[72];
double mjdref[2];
double timeoffs;
// Data timestamps and durations.
char dateobs[72], datebeg[72], dateavg[72], dateend[72];
double mjdobs, mjdbeg, mjdavg, mjdend;
double jepoch, bepoch;
double tstart, tstop;
double xposure, telapse;
// Timing accuracy.
double timsyer, timrder;
double timedel, timepixr;
// Spatial & celestial reference frame.
double obsgeo[6];
char obsorbit[72];
char radesys[72];
double equinox;
char specsys[72];
char ssysobs[72];
double velosys;
double zsource;
char ssyssrc[72];
double velangl;
// Additional auxiliary coordinate system information of a specialist
// nature. Not used by WCSLIB. Refer to the prologue comments above.
struct auxprm *aux;
// Coordinate lookup tables (see the prologue above).
//--------------------------------------------------------------------------
int ntab; // Number of separate tables.
int nwtb; // Number of wtbarr structs.
struct tabprm *tab; // Tabular transformation parameters.
struct wtbarr *wtb; // Array of wtbarr structs.
//--------------------------------------------------------------------------
// Information derived from the FITS header keyvalues by wcsset().
//--------------------------------------------------------------------------
char lngtyp[8], lattyp[8]; // Celestial axis types, e.g. RA, DEC.
int lng, lat, spec, time; // Longitude, latitude, spectral, and time
// axis indices (0-relative).
int cubeface; // True if there is a CUBEFACE axis.
int chksum; // Checksum of keyvalues provided.
int *types; // Coordinate type codes for each axis.
struct linprm lin; // Linear transformation parameters.
struct celprm cel; // Celestial transformation parameters.
struct spcprm spc; // Spectral transformation parameters.
// Error messaging, if enabled.
//--------------------------------------------------------------------------
struct wcserr *err;
//--------------------------------------------------------------------------
// Private - the remainder are for internal use.
//--------------------------------------------------------------------------
// Memory management.
int m_flag, m_naxis;
double *m_crpix, *m_pc, *m_cdelt, *m_crval;
char (*m_cunit)[72], (*m_ctype)[72];
struct pvcard *m_pv;
struct pscard *m_ps;
double *m_cd, *m_crota;
int *m_colax;
char (*m_cname)[72];
double *m_crder, *m_csyer, *m_czphs, *m_cperi;
struct auxprm *m_aux;
struct tabprm *m_tab;
struct wtbarr *m_wtb;
};
// Size of the wcsprm struct in int units, used by the Fortran wrappers.
#define WCSLEN (sizeof(struct wcsprm)/sizeof(int))
int wcsnpv(int n);
int wcsnps(int n);
int wcsini(int alloc, int naxis, struct wcsprm *wcs);
int wcsinit(int alloc, int naxis, struct wcsprm *wcs, int npvmax, int npsmax,
int ndpmax);
int wcsauxi(int alloc, struct wcsprm *wcs);
int wcssub(int alloc, const struct wcsprm *wcssrc, int *nsub, int axes[],
struct wcsprm *wcsdst);
int wcscompare(int cmp, double tol, const struct wcsprm *wcs1,
const struct wcsprm *wcs2, int *equal);
int wcsfree(struct wcsprm *wcs);
int wcstrim(struct wcsprm *wcs);
int wcssize(const struct wcsprm *wcs, int sizes[2]);
int auxsize(const struct auxprm *aux, int sizes[2]);
int wcsenq(const struct wcsprm *wcs, int enquiry);
int wcsprt(const struct wcsprm *wcs);
int wcsperr(const struct wcsprm *wcs, const char *prefix);
int wcsbchk(struct wcsprm *wcs, int bounds);
int wcsset(struct wcsprm *wcs);
int wcsp2s(struct wcsprm *wcs, int ncoord, int nelem, const double pixcrd[],
double imgcrd[], double phi[], double theta[], double world[],
int stat[]);
int wcss2p(struct wcsprm *wcs, int ncoord, int nelem, const double world[],
double phi[], double theta[], double imgcrd[], double pixcrd[],
int stat[]);
int wcsmix(struct wcsprm *wcs, int mixpix, int mixcel, const double vspan[2],
double vstep, int viter, double world[], double phi[],
double theta[], double imgcrd[], double pixcrd[]);
int wcsccs(struct wcsprm *wcs, double lng2p1, double lat2p1, double lng1p2,
const char *clng, const char *clat, const char *radesys,
double equinox, const char *alt);
int wcssptr(struct wcsprm *wcs, int *i, char ctype[9]);
const char* wcslib_version(int vers[3]);
// Defined mainly for backwards compatibility, use wcssub() instead.
#define wcscopy(alloc, wcssrc, wcsdst) wcssub(alloc, wcssrc, 0x0, 0x0, wcsdst)
// Deprecated.
#define wcsini_errmsg wcs_errmsg
#define wcssub_errmsg wcs_errmsg
#define wcscopy_errmsg wcs_errmsg
#define wcsfree_errmsg wcs_errmsg
#define wcsprt_errmsg wcs_errmsg
#define wcsset_errmsg wcs_errmsg
#define wcsp2s_errmsg wcs_errmsg
#define wcss2p_errmsg wcs_errmsg
#define wcsmix_errmsg wcs_errmsg
#ifdef __cplusplus
#undef wtbarr
}
#endif
#endif // WCSLIB_WCS
cel.h
lin.h
spc.h
auxprm
Additional auxiliary parameters.
Definition wcs.h:2114
auxprm::dsun_obs
double dsun_obs
Definition wcs.h:2116
auxprm::hglt_obs
double hglt_obs
Definition wcs.h:2119
auxprm::c_radius
double c_radius
Definition wcs.h:2123
auxprm::hgln_obs
double hgln_obs
Definition wcs.h:2118
auxprm::dummy
double dummy[2]
Definition wcs.h:2127
auxprm::crln_obs
double crln_obs
Definition wcs.h:2117
auxprm::b_radius
double b_radius
Definition wcs.h:2122
auxprm::blon_obs
double blon_obs
Definition wcs.h:2124
auxprm::a_radius
double a_radius
Definition wcs.h:2121
auxprm::rsun_ref
double rsun_ref
Definition wcs.h:2115
auxprm::bdis_obs
double bdis_obs
Definition wcs.h:2126
auxprm::blat_obs
double blat_obs
Definition wcs.h:2125
celprm
Celestial transformation parameters.
Definition cel.h:456
linprm
Linear transformation parameters.
Definition lin.h:718
pscard
Store for PSi_ma keyrecords.
Definition wcs.h:2104
pscard::i
int i
Definition wcs.h:2105
pscard::value
char value[72]
Definition wcs.h:2107
pscard::m
int m
Definition wcs.h:2106
pvcard
Store for PVi_ma keyrecords.
Definition wcs.h:2094
pvcard::value
double value
Definition wcs.h:2097
pvcard::i
int i
Definition wcs.h:2095
pvcard::m
int m
Definition wcs.h:2096
spcprm
Spectral transformation parameters.
Definition spc.h:869
tabprm
Tabular transformation parameters.
Definition tab.h:611
wcserr
Error message handling.
Definition wcserr.h:243
wcsprm
Coordinate transformation parameters.
Definition wcs.h:2134
wcsprm::m_wtb
struct wtbarr * m_wtb
Definition wcs.h:2259
wcsprm::crpix
double * crpix
Definition wcs.h:2142
wcsprm::mjdavg
double mjdavg
Definition wcs.h:2196
wcsprm::plephem
char plephem[72]
Definition wcs.h:2189
wcsprm::lng
int lng
Definition wcs.h:2230
wcsprm::zsource
double zsource
Definition wcs.h:2211
wcsprm::m_crpix
double * m_crpix
Definition wcs.h:2249
wcsprm::ssysobs
char ssysobs[72]
Definition wcs.h:2209
wcsprm::npv
int npv
Definition wcs.h:2156
wcsprm::timrder
double timrder
Definition wcs.h:2201
wcsprm::telapse
double telapse
Definition wcs.h:2199
wcsprm::timeunit
char timeunit[72]
Definition wcs.h:2190
wcsprm::m_csyer
double * m_csyer
Definition wcs.h:2256
wcsprm::tstart
double tstart
Definition wcs.h:2198
wcsprm::mjdend
double mjdend
Definition wcs.h:2196
wcsprm::csyer
double * csyer
Definition wcs.h:2183
wcsprm::types
int * types
Definition wcs.h:2234
wcsprm::m_cname
char(* m_cname)[72]
Definition wcs.h:2255
wcsprm::obsorbit
char obsorbit[72]
Definition wcs.h:2205
wcsprm::mjdref
double mjdref[2]
Definition wcs.h:2192
wcsprm::m_crder
double * m_crder
Definition wcs.h:2256
wcsprm::crota
double * crota
Definition wcs.h:2167
wcsprm::lngtyp
char lngtyp[8]
Definition wcs.h:2229
wcsprm::lin
struct linprm lin
Definition wcs.h:2236
wcsprm::m_cunit
char(* m_cunit)[72]
Definition wcs.h:2250
wcsprm::flag
int flag
Definition wcs.h:2137
wcsprm::radesys
char radesys[72]
Definition wcs.h:2206
wcsprm::ctype
char(* ctype)[72]
Definition wcs.h:2148
wcsprm::npsmax
int npsmax
Definition wcs.h:2161
wcsprm::m_cdelt
double * m_cdelt
Definition wcs.h:2249
wcsprm::aux
struct auxprm * aux
Definition wcs.h:2217
wcsprm::trefpos
char trefpos[72]
Definition wcs.h:2189
wcsprm::pv
struct pvcard * pv
Definition wcs.h:2158
wcsprm::timeoffs
double timeoffs
Definition wcs.h:2193
wcsprm::nps
int nps
Definition wcs.h:2160
wcsprm::m_ps
struct pscard * m_ps
Definition wcs.h:2252
wcsprm::m_crval
double * m_crval
Definition wcs.h:2249
wcsprm::timepixr
double timepixr
Definition wcs.h:2202
wcsprm::cname
char(* cname)[72]
Definition wcs.h:2181
wcsprm::m_crota
double * m_crota
Definition wcs.h:2253
wcsprm::m_cperi
double * m_cperi
Definition wcs.h:2256
wcsprm::tab
struct tabprm * tab
Definition wcs.h:2223
wcsprm::m_flag
int m_flag
Definition wcs.h:2248
wcsprm::alt
char alt[4]
Definition wcs.h:2177
wcsprm::restwav
double restwav
Definition wcs.h:2154
wcsprm::latpole
double latpole
Definition wcs.h:2151
wcsprm::m_naxis
int m_naxis
Definition wcs.h:2248
wcsprm::chksum
int chksum
Definition wcs.h:2233
wcsprm::dateavg
char dateavg[72]
Definition wcs.h:2195
wcsprm::colax
int * colax
Definition wcs.h:2179
wcsprm::m_tab
struct tabprm * m_tab
Definition wcs.h:2258
wcsprm::m_pc
double * m_pc
Definition wcs.h:2249
wcsprm::datebeg
char datebeg[72]
Definition wcs.h:2195
wcsprm::m_pv
struct pvcard * m_pv
Definition wcs.h:2251
wcsprm::naxis
int naxis
Definition wcs.h:2141
wcsprm::m_czphs
double * m_czphs
Definition wcs.h:2256
wcsprm::m_colax
int * m_colax
Definition wcs.h:2254
wcsprm::tstop
double tstop
Definition wcs.h:2198
wcsprm::timesys
char timesys[72]
Definition wcs.h:2189
wcsprm::timsyer
double timsyer
Definition wcs.h:2201
wcsprm::nwtb
int nwtb
Definition wcs.h:2222
wcsprm::ps
struct pscard * ps
Definition wcs.h:2162
wcsprm::cperi
double * cperi
Definition wcs.h:2185
wcsprm::equinox
double equinox
Definition wcs.h:2207
wcsprm::altlin
int altlin
Definition wcs.h:2168
wcsprm::npvmax
int npvmax
Definition wcs.h:2157
wcsprm::jepoch
double jepoch
Definition wcs.h:2197
wcsprm::wcsname
char wcsname[72]
Definition wcs.h:2187
wcsprm::obsgeo
double obsgeo[6]
Definition wcs.h:2204
wcsprm::ntab
int ntab
Definition wcs.h:2221
wcsprm::m_cd
double * m_cd
Definition wcs.h:2253
wcsprm::colnum
int colnum
Definition wcs.h:2178
wcsprm::velangl
double velangl
Definition wcs.h:2213
wcsprm::mjdbeg
double mjdbeg
Definition wcs.h:2196
wcsprm::dateend
char dateend[72]
Definition wcs.h:2195
wcsprm::trefdir
char trefdir[72]
Definition wcs.h:2189
wcsprm::bepoch
double bepoch
Definition wcs.h:2197
wcsprm::specsys
char specsys[72]
Definition wcs.h:2208
wcsprm::cunit
char(* cunit)[72]
Definition wcs.h:2147
wcsprm::time
int time
Definition wcs.h:2230
wcsprm::ssyssrc
char ssyssrc[72]
Definition wcs.h:2212
wcsprm::dateref
char dateref[72]
Definition wcs.h:2191
wcsprm::wtb
struct wtbarr * wtb
Definition wcs.h:2224
wcsprm::czphs
double * czphs
Definition wcs.h:2184
wcsprm::cdelt
double * cdelt
Definition wcs.h:2144
wcsprm::pc
double * pc
Definition wcs.h:2143
wcsprm::lat
int lat
Definition wcs.h:2230
wcsprm::spec
int spec
Definition wcs.h:2230
wcsprm::cd
double * cd
Definition wcs.h:2166
wcsprm::mjdobs
double mjdobs
Definition wcs.h:2196
wcsprm::xposure
double xposure
Definition wcs.h:2199
wcsprm::velref
int velref
Definition wcs.h:2172
wcsprm::cel
struct celprm cel
Definition wcs.h:2237
wcsprm::lattyp
char lattyp[8]
Definition wcs.h:2229
wcsprm::crval
double * crval
Definition wcs.h:2145
wcsprm::crder
double * crder
Definition wcs.h:2182
wcsprm::m_aux
struct auxprm * m_aux
Definition wcs.h:2257
wcsprm::restfrq
double restfrq
Definition wcs.h:2153
wcsprm::cubeface
int cubeface
Definition wcs.h:2232
wcsprm::spc
struct spcprm spc
Definition wcs.h:2238
wcsprm::timedel
double timedel
Definition wcs.h:2202
wcsprm::err
struct wcserr * err
Definition wcs.h:2242
wcsprm::velosys
double velosys
Definition wcs.h:2210
wcsprm::lonpole
double lonpole
Definition wcs.h:2150
wcsprm::dateobs
char dateobs[72]
Definition wcs.h:2195
wtbarr
Extraction of coordinate lookup tables from BINTABLE.
Definition getwcstab.h:167
wtbarr::i
int i
Definition getwcstab.h:168
wcs_errmsg_enum
wcs_errmsg_enum
Definition wcs.h:2068
WCSERR_BAD_WORLD
@ WCSERR_BAD_WORLD
Definition wcs.h:2082
WCSERR_BAD_PIX
@ WCSERR_BAD_PIX
Definition wcs.h:2080
WCSERR_SINGULAR_MTX
@ WCSERR_SINGULAR_MTX
Definition wcs.h:2072
WCSERR_NON_SEPARABLE
@ WCSERR_NON_SEPARABLE
Definition wcs.h:2088
WCSERR_BAD_CTYPE
@ WCSERR_BAD_CTYPE
Definition wcs.h:2073
WCSERR_MEMORY
@ WCSERR_MEMORY
Definition wcs.h:2071
WCSERR_BAD_WORLD_COORD
@ WCSERR_BAD_WORLD_COORD
Definition wcs.h:2084
WCSERR_BAD_COORD_TRANS
@ WCSERR_BAD_COORD_TRANS
Definition wcs.h:2076
WCSERR_NO_SOLUTION
@ WCSERR_NO_SOLUTION
Definition wcs.h:2085
WCSERR_BAD_SUBIMAGE
@ WCSERR_BAD_SUBIMAGE
Definition wcs.h:2087
WCSERR_SUCCESS
@ WCSERR_SUCCESS
Definition wcs.h:2069
WCSERR_UNSET
@ WCSERR_UNSET
Definition wcs.h:2089
WCSERR_NULL_POINTER
@ WCSERR_NULL_POINTER
Definition wcs.h:2070
WCSERR_ILL_COORD_TRANS
@ WCSERR_ILL_COORD_TRANS
Definition wcs.h:2078
WCSERR_BAD_PARAM
@ WCSERR_BAD_PARAM
Definition wcs.h:2075
wcsmix
int wcsmix(struct wcsprm *wcs, int mixpix, int mixcel, const double vspan[2], double vstep, int viter, double world[], double phi[], double theta[], double imgcrd[], double pixcrd[])
Hybrid coordinate transformation.
wcsp2s
int wcsp2s(struct wcsprm *wcs, int ncoord, int nelem, const double pixcrd[], double imgcrd[], double phi[], double theta[], double world[], int stat[])
Pixel-to-world transformation.
wcsini
int wcsini(int alloc, int naxis, struct wcsprm *wcs)
Default constructor for the wcsprm struct.
wcssize
int wcssize(const struct wcsprm *wcs, int sizes[2])
Compute the size of a wcsprm struct.
wcsnpv
int wcsnpv(int n)
Memory allocation for PVi_ma.
wcsfree
int wcsfree(struct wcsprm *wcs)
Destructor for the wcsprm struct.
auxsize
int auxsize(const struct auxprm *aux, int sizes[2])
Compute the size of a auxprm struct.
wcssptr
int wcssptr(struct wcsprm *wcs, int *i, char ctype[9])
Spectral axis translation.
wcss2p
int wcss2p(struct wcsprm *wcs, int ncoord, int nelem, const double world[], double phi[], double theta[], double imgcrd[], double pixcrd[], int stat[])
World-to-pixel transformation.
wcscompare
int wcscompare(int cmp, double tol, const struct wcsprm *wcs1, const struct wcsprm *wcs2, int *equal)
Compare two wcsprm structs for equality.
wcsccs
int wcsccs(struct wcsprm *wcs, double lng2p1, double lat2p1, double lng1p2, const char *clng, const char *clat, const char *radesys, double equinox, const char *alt)
Change celestial coordinate system.
wcs_errmsg
const char * wcs_errmsg[]
Status return messages.
wcssub
int wcssub(int alloc, const struct wcsprm *wcssrc, int *nsub, int axes[], struct wcsprm *wcsdst)
Subimage extraction routine for the wcsprm struct.
wcsperr
int wcsperr(const struct wcsprm *wcs, const char *prefix)
Print error messages from a wcsprm struct.
wcsauxi
int wcsauxi(int alloc, struct wcsprm *wcs)
Default constructor for the auxprm struct.
wcsinit
int wcsinit(int alloc, int naxis, struct wcsprm *wcs, int npvmax, int npsmax, int ndpmax)
Default constructor for the wcsprm struct.
wcstrim
int wcstrim(struct wcsprm *wcs)
Free unused arrays in the wcsprm struct.
wcsprt
int wcsprt(const struct wcsprm *wcs)
Print routine for the wcsprm struct.
wcslib_version
const char * wcslib_version(int vers[3])
wcsenq_enum
wcsenq_enum
Definition wcs.h:2045
WCSENQ_SET
@ WCSENQ_SET
Definition wcs.h:2047
WCSENQ_CHK
@ WCSENQ_CHK
Definition wcs.h:2049
WCSENQ_MEM
@ WCSENQ_MEM
Definition wcs.h:2046
WCSENQ_BYP
@ WCSENQ_BYP
Definition wcs.h:2048
wcsset
int wcsset(struct wcsprm *wcs)
Setup routine for the wcsprm struct.
wcsnps
int wcsnps(int n)
Memory allocation for PSi_ma.
wcsenq
int wcsenq(const struct wcsprm *wcs, int enquiry)
enquire about the state of a wcsprm struct.
wcsbchk
int wcsbchk(struct wcsprm *wcs, int bounds)
Enable/disable bounds checking.