wcs.h
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/*============================================================================
WCSLIB 5.3 - an implementation of the FITS WCS standard.
Copyright (C) 1995-2015, 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.
Direct correspondence concerning WCSLIB to mark@calabretta.id.au
Author: Mark Calabretta, Australia Telescope National Facility, CSIRO.
http://www.atnf.csiro.au/people/Mark.Calabretta
$Id: wcs.h,v 5.3.1.1 2015/04/21 02:54:02 mcalabre Exp mcalabre $
*=============================================================================
*
* WCSLIB 5.3 - C routines that implement the FITS World Coordinate System
* (WCS) standard. Refer to
*
* "Representations of world coordinates in FITS",
* Greisen, E.W., & Calabretta, M.R. 2002, A&A, 395, 1061 (Paper I)
*
* "Representations of celestial coordinates in FITS",
* Calabretta, M.R., & Greisen, E.W. 2002, A&A, 395, 1077 (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 (Paper III)
*
* Refer to the README file provided with WCSLIB for an overview of the
* library.
*
*
* Summary of the wcs routines
* ---------------------------
* These routines 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. They 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(), wcssub(), and wcsfree() are provided to manage
* the wcsprm struct and another, wcsprt(), prints its contents. Refer to the
* description of the wcsprm struct for an explanation of the anticipated usage
* of these routines. 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.
*
* wcssptr() translates the spectral axis in a wcsprm struct. 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() changes 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.
*
* PLEASE NOTE: This function is not thread-safe.
*
* Given:
* n int Value of NPVMAX; ignored if < 0.
*
* Function return value:
* int Current value of NPVMAX.
*
*
* wcsnps() - Memory allocation for PSi_ma
* ---------------------------------------
* wcsnps() changes the values of NPSMAX (default 8). This global variable
* controls the number of pscard structs, for holding PSi_ma keyvalues, that
* wcsini() should allocate space for.
*
* PLEASE NOTE: This function is not thread-safe.
*
* Given:
* n int Value of NPSMAX; ignored if < 0.
*
* Function return value:
* int Current value of NPSMAX.
*
*
* wcsini() - Default constructor for the wcsprm struct
* ----------------------------------------------------
* wcsini() optionally allocates memory for arrays in a wcsprm struct and sets
* all members of the struct to default values. Memory is allocated for up to
* NPVMAX PVi_ma keywords or NPSMAX PSi_ma keywords per WCS representation.
* These may be changed via wcsnpv() and wcsnps() before wcsini() is called.
*
* PLEASE NOTE: every wcsprm struct should be initialized by wcsini(), 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 wcsini() will actually be used to allocate memory.
*
* Given:
* alloc int If true, allocate memory unconditionally for the
* crpix, etc. arrays.
*
* 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).
*
* 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().
*
*
* 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 wcsini() to allocate memory for its
* arrays if required. Only the "information to be provided" part of the
* struct is extracted; a call to wcsset() is required to set up the remainder.
*
* 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 PCi_ja 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.
*
* 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 wcsini() 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 wcsini(). 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.
*
* 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:
* 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 grid map. 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 wcsini() and/or
* wcsset(). wcsini() 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 wcsini().
*
* Returned:
* wcs struct wcsprm*
* Coordinate transformation parameters.
*
* Function return value:
* int Status return value:
* 0: Success.
* 1: Null wcsprm pointer passed.
*
*
* 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.
*
* 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:
* 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.
*
* 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, imgcrd[][wcs.spec] is the intermediate
* spectral coordinate, in SI units.
*
* 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.
*
* 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.
*
* 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:
* 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.
*
*
* 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.
*
* 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 wcsini() 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 wcsini() 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 whenever any of the
* following wcsprm struct 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 celprm struct. celset() will reset flag to
* indicate that this has been done.
*
* PLEASE NOTE: flag should be set to -1 when wcsini() 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 wcsini() 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 wcsini()
* (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 wcsini(), 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 wcsini() 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 wcsini() 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 CROTAia 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 CROTAia 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 CROTAia) 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 CROTAia which are to be ignored.
*
* - Bit 2: CROTAia is present.
*
* In the AIPS convention, CROTAia 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 CROTAia keywords are ignored.
*
* CROTAia may not formally co-exist with PCi_ja.
*
* CROTAia and CDELTia may formally co-exist with CDi_ja but if so are to
* be ignored.
*
* CDi_ja and CROTAia 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 CROTAia 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, wcsset() resets
* wcsprm::cdelt to unity if CDi_ja is present (and no PCi_ja).
*
* If CROTAia 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.
*
* char dateavg[72]
* (Given, auxiliary) The date of 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 dateobs[72]
* (Given, auxiliary) The date of the start of the observation unless
* otherwise explained in the comment field of the DATE-OBS keyword, in
* ISO format, yyyy-mm-ddThh:mm:ss.
*
* It is not necessary to reset the wcsprm struct (via wcsset()) when
* wcsprm::dateobs 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.
*
* double mjdavg
* (Given, auxiliary) Modified Julian Date (MJD = JD - 2400000.5), MJD-AVG,
* corresponding to DATE-AVG.
*
* It is not necessary to reset the wcsprm struct (via wcsset()) when
* wcsprm::mjdavg is changed.
*
* double mjdobs
* (Given, auxiliary) Modified Julian Date (MJD = JD - 2400000.5), MJD-OBS,
* corresponding to DATE-OBS.
*
* It is not necessary to reset the wcsprm struct (via wcsset()) when
* wcsprm::mjdobs is changed.
*
* double obsgeo[3]
* (Given, auxiliary) Location of the observer in a standard terrestrial
* reference frame, OBSGEO-X, OBSGEO-Y, OBSGEO-Z [m].
*
* It is not necessary to reset the wcsprm struct (via wcsset()) when
* wcsprm::obsgeo 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.
*
* 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.
*
* 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.
*
* 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 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 *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.
*
* - 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.
*
* void *padding
* (An unused variable inserted for alignment purposes only.)
*
* 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().
*
* void *m_padding
* (For internal use only.)
* 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.)
* 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.
*
*
* wtbarr struct - Extraction of coordinate lookup tables from BINTABLE
* --------------------------------------------------------------------
* Function wcstab(), which is invoked automatically by wcspih(), sets up an
* array of wtbarr structs to assist in extracting coordinate lookup tables
* from a binary table extension (BINTABLE) and copying them into the tabprm
* structs stored in wcsprm. Refer to the usage notes for wcspih() and
* wcstab() in wcshdr.h, and also the prologue to tab.h.
*
* For C++ usage, because of a name space conflict with the wtbarr typedef
* defined in CFITSIO header fitsio.h, the wtbarr struct is renamed to wtbarr_s
* by preprocessor macro substitution with scope limited to wcs.h itself.
*
* int i
* (Given) Image axis number.
*
* int m
* (Given) wcstab array axis number for index vectors.
*
* int kind
* (Given) Character identifying the wcstab array type:
* - c: coordinate array,
* - i: index vector.
*
* char extnam[72]
* (Given) EXTNAME identifying the binary table extension.
*
* int extver
* (Given) EXTVER identifying the binary table extension.
*
* int extlev
* (Given) EXTLEV identifying the binary table extension.
*
* char ttype[72]
* (Given) TTYPEn identifying the column of the binary table that contains
* the wcstab array.
*
* long row
* (Given) Table row number.
*
* int ndim
* (Given) Expected dimensionality of the wcstab array.
*
* int *dimlen
* (Given) Address of the first element of an array of int of length ndim
* into which the wcstab array axis lengths are to be written.
*
* double **arrayp
* (Given) Pointer to an array of double which is to be allocated by the
* user and into which the wcstab array is to be written.
*
*
* 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" {
#endif
#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 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. */
};
/* 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))
/* For extracting wcstab arrays. Matches */
/* the wtbarr typedef defined in CFITSIO */
/* header fitsio.h. */
#ifdef __cplusplus
#define wtbarr wtbarr_s /* See prologue above. */
#endif
struct wtbarr {
int i; /* Image axis number. */
int m; /* Array axis number for index vectors. */
int kind; /* wcstab array type. */
char extnam[72]; /* EXTNAME of binary table extension. */
int extver; /* EXTVER of binary table extension. */
int extlev; /* EXTLEV of binary table extension. */
char ttype[72]; /* TTYPEn of column containing the array. */
long row; /* Table row number. */
int ndim; /* Expected wcstab array dimensionality. */
int *dimlen; /* Where to write the array axis lengths. */
double **arrayp; /* Where to write the address of the array */
/* allocated to store the wcstab array. */
};
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; /* CROTAia keyvalues for each coord axis. */
int altlin; /* Alternative representations */
/* Bit 0: PCi_ja is present, */
/* Bit 1: CDi_ja is present, */
/* Bit 2: CROTAia is present. */
int velref; /* AIPS velocity code, VELREF. */
/* Auxiliary coordinate system information, not used by WCSLIB. */
char alt[4];
int colnum;
int *colax;
char (*cname)[72];
double *crder;
double *csyer;
char dateavg[72];
char dateobs[72];
double equinox;
double mjdavg;
double mjdobs;
double obsgeo[3];
char radesys[72];
char specsys[72];
char ssysobs[72];
double velosys;
double zsource;
char ssyssrc[72];
double velangl;
char wcsname[72];
/* 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; /* Longitude, latitude and spectral axis */
/* indices (0-relative). */
int cubeface; /* True if there is a CUBEFACE axis. */
int *types; /* Coordinate type codes for each axis. */
void *padding; /* (Dummy inserted for alignment purposes.) */
struct linprm lin; /* Linear transformation parameters. */
struct celprm cel; /* Celestial transformation parameters. */
struct spcprm spc; /* Spectral transformation parameters. */
/* Error handling, if enabled. */
/*------------------------------------------------------------------------*/
struct wcserr *err;
/* Private - the remainder are for memory management. */
/*------------------------------------------------------------------------*/
void *m_padding;
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;
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 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 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[],
double vstep, int viter, double world[], double phi[],
double theta[], double imgcrd[], double pixcrd[]);
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 */
WCSERR_BAD_PIX
Definition: wcs.h:1515
wcsprm::dateobs
char dateobs[72]
Definition: wcs.h:1619
wcsfree
int wcsfree(struct wcsprm *wcs)
Destructor for the wcsprm struct.
wcsprm::radesys
char radesys[72]
Definition: wcs.h:1624
wcsprm::m_wtb
struct wtbarr * m_wtb
Definition: wcs.h:1670
WCSERR_MEMORY
Definition: wcs.h:1505
wcssub
int wcssub(int alloc, const struct wcsprm *wcssrc, int *nsub, int axes[], struct wcsprm *wcsdst)
Subimage extraction routine for the wcsprm struct.
wtbarr::kind
int kind
Definition: getwcstab.h:169
wcsprm::m_crval
double * m_crval
Definition: wcs.h:1661
WCSERR_NON_SEPARABLE
Definition: wcs.h:1523
wcsprm::cd
double * cd
Definition: wcs.h:1602
wcsprm::m_colax
int * m_colax
Definition: wcs.h:1666
wcsprm::ps
struct pscard * ps
Definition: wcs.h:1598
wcsprm::cdelt
double * cdelt
Definition: wcs.h:1580
pvcard::i
int i
Definition: wcs.h:1530
lin.h
wcsprm::npv
int npv
Definition: wcs.h:1592
cel.h
wcsprm::tab
struct tabprm * tab
Definition: wcs.h:1637
wtbarr::ttype
char ttype[72]
Definition: getwcstab.h:173
wcsprm::err
struct wcserr * err
Definition: wcs.h:1655
wcsprm::lng
int lng
Definition: wcs.h:1643
wcsprm::m_cunit
char(* m_cunit)[72]
Definition: wcs.h:1662
wcsprm::npsmax
int npsmax
Definition: wcs.h:1597
wcsprm::alt
char alt[4]
Definition: wcs.h:1611
wcsprm::m_cname
char(* m_cname)[72]
Definition: wcs.h:1667
wcserr
Error message handling.
Definition: wcserr.h:221
wtbarr::i
int i
Definition: getwcstab.h:167
wcsprm::spc
struct spcprm spc
Definition: wcs.h:1651
wcsprm::cubeface
int cubeface
Definition: wcs.h:1645
wcsprm::flag
int flag
Definition: wcs.h:1573
wcsprm::equinox
double equinox
Definition: wcs.h:1620
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.
pvcard::m
int m
Definition: wcs.h:1531
wcsbchk
int wcsbchk(struct wcsprm *wcs, int bounds)
Enable/disable bounds checking.
wcsprm::obsgeo
double obsgeo[3]
Definition: wcs.h:1623
WCSERR_BAD_SUBIMAGE
Definition: wcs.h:1522
wcsprm::lonpole
double lonpole
Definition: wcs.h:1586
wcsprm::nps
int nps
Definition: wcs.h:1596
wcsprm::pv
struct pvcard * pv
Definition: wcs.h:1594
wtbarr::m
int m
Definition: getwcstab.h:168
WCSERR_SINGULAR_MTX
Definition: wcs.h:1506
WCSERR_SUCCESS
Definition: wcs.h:1503
spcprm
Spectral transformation parameters.
Definition: spc.h:773
WCSERR_BAD_PARAM
Definition: wcs.h:1510
wcsprm::m_tab
struct tabprm * m_tab
Definition: wcs.h:1669
celprm
Celestial transformation parameters.
Definition: cel.h:392
linprm
Linear transformation parameters.
Definition: lin.h:599
wcs_errmsg_enum
wcs_errmsg_enum
Definition: wcs.h:1502
wcsprm::m_ps
struct pscard * m_ps
Definition: wcs.h:1664
wcsprt
int wcsprt(const struct wcsprm *wcs)
Print routine for the wcsprm struct.
WCSERR_NULL_POINTER
Definition: wcs.h:1504
wcsprm::cunit
char(* cunit)[72]
Definition: wcs.h:1583
wcsprm::ntab
int ntab
Definition: wcs.h:1635
spc.h
wcsprm::crota
double * crota
Definition: wcs.h:1603
wcscompare
int wcscompare(int cmp, double tol, const struct wcsprm *wcs1, const struct wcsprm *wcs2, int *equal)
Compare two wcsprm structs for equality.
wcsprm::m_naxis
int m_naxis
Definition: wcs.h:1660
wcsprm::m_cd
double * m_cd
Definition: wcs.h:1665
wtbarr::row
long row
Definition: getwcstab.h:174
wcsprm::restfrq
double restfrq
Definition: wcs.h:1589
wcsprm::specsys
char specsys[72]
Definition: wcs.h:1625
wcsprm::types
int * types
Definition: wcs.h:1646
wcssptr
int wcssptr(struct wcsprm *wcs, int *i, char ctype[9])
Spectral axis translation.
pscard::value
char value[72]
Definition: wcs.h:1542
wcsprm::nwtb
int nwtb
Definition: wcs.h:1636
wcsprm::dateavg
char dateavg[72]
Definition: wcs.h:1618
wcsprm::ssysobs
char ssysobs[72]
Definition: wcs.h:1626
wcsprm::cname
char(* cname)[72]
Definition: wcs.h:1615
wtbarr::arrayp
double ** arrayp
Definition: getwcstab.h:177
wcsset
int wcsset(struct wcsprm *wcs)
Setup routine for the wcsprm struct.
wcsprm
Coordinate transformation parameters.
Definition: wcs.h:1570
wcsprm::colnum
int colnum
Definition: wcs.h:1612
WCSERR_BAD_COORD_TRANS
Definition: wcs.h:1511
wcsprm::m_pc
double * m_pc
Definition: wcs.h:1661
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.
wcsprm::velangl
double velangl
Definition: wcs.h:1630
wcsprm::wtb
struct wtbarr * wtb
Definition: wcs.h:1638
wcsprm::crder
double * crder
Definition: wcs.h:1616
wcsprm::restwav
double restwav
Definition: wcs.h:1590
wcsprm::m_crder
double * m_crder
Definition: wcs.h:1668
wcsprm::lngtyp
char lngtyp[8]
Definition: wcs.h:1642
wcsnpv
int wcsnpv(int n)
Memory allocation for PVi_ma.
wcsprm::naxis
int naxis
Definition: wcs.h:1577
pscard::m
int m
Definition: wcs.h:1541
wcsmix
int wcsmix(struct wcsprm *wcs, int mixpix, int mixcel, const double vspan[], double vstep, int viter, double world[], double phi[], double theta[], double imgcrd[], double pixcrd[])
Hybrid coordinate transformation.
wcsprm::spec
int spec
Definition: wcs.h:1643
wcs_errmsg
const char * wcs_errmsg[]
Status return messages.
WCSERR_BAD_WORLD_COORD
Definition: wcs.h:1519
wtbarr
Extraction of coordinate lookup tables from BINTABLE.
Definition: getwcstab.h:166
wcsperr
int wcsperr(const struct wcsprm *wcs, const char *prefix)
Print error messages from a wcsprm struct.
wcsprm::latpole
double latpole
Definition: wcs.h:1587
wcsprm::m_crpix
double * m_crpix
Definition: wcs.h:1661
wcsprm::velosys
double velosys
Definition: wcs.h:1627
wcsprm::m_csyer
double * m_csyer
Definition: wcs.h:1668
WCSERR_ILL_COORD_TRANS
Definition: wcs.h:1513
tabprm
Tabular transformation parameters.
Definition: tab.h:524
wcsprm::velref
int velref
Definition: wcs.h:1608
pscard::i
int i
Definition: wcs.h:1540
wcslib_version
const char * wcslib_version(int vers[3])
wcsprm::csyer
double * csyer
Definition: wcs.h:1617
wcsprm::m_padding
void * m_padding
Definition: wcs.h:1659
wcsprm::lat
int lat
Definition: wcs.h:1643
pvcard
Store for PVi_ma keyrecords.
Definition: wcs.h:1529
WCSERR_BAD_CTYPE
Definition: wcs.h:1508
wcsprm::crpix
double * crpix
Definition: wcs.h:1578
wcsprm::mjdavg
double mjdavg
Definition: wcs.h:1621
wcsprm::cel
struct celprm cel
Definition: wcs.h:1650
wcsini
int wcsini(int alloc, int naxis, struct wcsprm *wcs)
Default constructor for the wcsprm struct.
wtbarr::extnam
char extnam[72]
Definition: getwcstab.h:170
wcsprm::m_cdelt
double * m_cdelt
Definition: wcs.h:1661
wcsprm::npvmax
int npvmax
Definition: wcs.h:1593
pvcard::value
double value
Definition: wcs.h:1532
pscard
Store for PSi_ma keyrecords.
Definition: wcs.h:1539
wtbarr::ndim
int ndim
Definition: getwcstab.h:175
wcsprm::crval
double * crval
Definition: wcs.h:1581
wcsprm::colax
int * colax
Definition: wcs.h:1613
wcsprm::altlin
int altlin
Definition: wcs.h:1604
wcsprm::lin
struct linprm lin
Definition: wcs.h:1649
wcsprm::ctype
char(* ctype)[72]
Definition: wcs.h:1584
wcsprm::pc
double * pc
Definition: wcs.h:1579
wcsprm::mjdobs
double mjdobs
Definition: wcs.h:1622
wtbarr::extver
int extver
Definition: getwcstab.h:171
wcsprm::m_crota
double * m_crota
Definition: wcs.h:1665
WCSERR_NO_SOLUTION
Definition: wcs.h:1520
wtbarr::dimlen
int * dimlen
Definition: getwcstab.h:176
wcsprm::ssyssrc
char ssyssrc[72]
Definition: wcs.h:1629
wcsprm::lattyp
char lattyp[8]
Definition: wcs.h:1642
WCSERR_BAD_WORLD
Definition: wcs.h:1517
wcsprm::m_pv
struct pvcard * m_pv
Definition: wcs.h:1663
wcsprm::m_flag
int m_flag
Definition: wcs.h:1660
wtbarr::extlev
int extlev
Definition: getwcstab.h:172
wcsprm::zsource
double zsource
Definition: wcs.h:1628
wcsprm::padding
void * padding
Definition: wcs.h:1647
wcsprm::wcsname
char wcsname[72]
Definition: wcs.h:1631
wcsnps
int wcsnps(int n)
Memory allocation for PSi_ma.