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WCSLIB 8.4
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Coordinate transformation parameters. More...
#include <wcs.h>
Data Fields | |
| int | flag |
| int | naxis |
| double * | crpix |
| double * | pc |
| double * | cdelt |
| double * | crval |
| char(* | cunit )[72] |
| char(* | ctype )[72] |
| double | lonpole |
| double | latpole |
| double | restfrq |
| double | restwav |
| int | npv |
| int | npvmax |
| struct pvcard * | pv |
| int | nps |
| int | npsmax |
| struct pscard * | ps |
| double * | cd |
| double * | crota |
| int | altlin |
| int | velref |
| char | alt [4] |
| int | colnum |
| int * | colax |
| char(* | cname )[72] |
| double * | crder |
| double * | csyer |
| double * | czphs |
| double * | cperi |
| char | wcsname [72] |
| char | timesys [72] |
| char | trefpos [72] |
| char | trefdir [72] |
| char | plephem [72] |
| char | timeunit [72] |
| char | dateref [72] |
| double | mjdref [2] |
| double | timeoffs |
| char | dateobs [72] |
| char | datebeg [72] |
| char | dateavg [72] |
| char | dateend [72] |
| double | mjdobs |
| double | mjdbeg |
| double | mjdavg |
| double | mjdend |
| double | jepoch |
| double | bepoch |
| double | tstart |
| double | tstop |
| double | xposure |
| double | telapse |
| double | timsyer |
| double | timrder |
| double | timedel |
| double | timepixr |
| 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 |
| struct auxprm * | aux |
| int | ntab |
| int | nwtb |
| struct tabprm * | tab |
| struct wtbarr * | wtb |
| char | lngtyp [8] |
| char | lattyp [8] |
| int | lng |
| int | lat |
| int | spec |
| int | time |
| int | cubeface |
| int | chksum |
| int * | types |
| struct linprm | lin |
| struct celprm | cel |
| struct spcprm | spc |
| struct wcserr * | err |
| int | m_flag |
| int | m_naxis |
| double * | m_crpix |
| double * | m_pc |
| double * | m_cdelt |
| double * | m_crval |
| char(* | m_cunit )[72] |
| char((* | m_ctype )[72] |
| struct pvcard * | m_pv |
| struct pscard * | m_ps |
| double * | m_cd |
| double * | m_crota |
| int * | m_colax |
| char(* | m_cname )[72] |
| double * | m_crder |
| double * | m_csyer |
| double * | m_czphs |
| double * | m_cperi |
| struct auxprm * | m_aux |
| struct tabprm * | m_tab |
| struct wtbarr * | m_wtb |
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 wcsprm::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:
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 wcsprm::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* wcsprm::crpix |
(Given) Address of the first element of an array of double containing the coordinate reference pixel, CRPIXja.
| double* wcsprm::pc |
(Given) Address of the first element of the PCi_ja (pixel coordinate) transformation matrix. The expected order is
This may be constructed conveniently from a 2-D array via
which is equivalent to
The storage order for this 2-D array is the same as for the 1-D array, whence
would be legitimate.
| double* wcsprm::cdelt |
(Given) Address of the first element of an array of double containing the coordinate increments, CDELTia.
| double* wcsprm::crval |
(Given) Address of the first element of an array of double containing the coordinate reference values, CRVALia.
| char(* wcsprm::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(* wcsprm::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 wcsprm::lonpole |
(Given and returned) The native longitude of the celestial pole, 
LONPOLEa [deg] or by PVi_2a [deg] attached to the longitude axis which takes precedence if defined, and ...
| double wcsprm::latpole |
(Given and returned) ... the native latitude of the celestial pole, 
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 wcsprm::restfrq |
(Given) The rest frequency [Hz], and/or ...
| double wcsprm::restwav |
(Given) ... the rest wavelength in vacuo [m], only one of which need be given, the other should be set to zero.
| int wcsprm::npv |
(Given) The number of entries in the wcsprm::pv[] array.
| int wcsprm::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* wcsprm::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 wcsprm::nps |
(Given) The number of entries in the wcsprm::ps[] array.
| int wcsprm::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* wcsprm::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* wcsprm::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* wcsprm::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 wcsprm::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:
Whenever a CDi_ja keyword is encountered:
CROTAi keyword is encountered: 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 wcsprm::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 wcsprm::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 wcsprm::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* wcsprm::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(* wcsprm::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* wcsprm::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* wcsprm::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* wcsprm::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* wcsprm::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 wcsprm::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 wcsprm::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 wcsprm::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 wcsprm::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 wcsprm::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 wcsprm::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 wcsprm::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 wcsprm::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 wcsprm::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 wcsprm::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 wcsprm::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 wcsprm::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 wcsprm::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 wcsprm::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 wcsprm::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 wcsprm::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 wcsprm::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 wcsprm::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 wcsprm::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 wcsprm::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 wcsprm::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 wcsprm::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 wcsprm::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 wcsprm::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 wcsprm::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 wcsprm::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 wcsprm::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 wcsprm::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 wcsprm::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 wcsprm::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 wcsprm::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 wcsprm::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 wcsprm::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 wcsprm::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 wcsprm::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 wcsprm::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 wcsprm::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* wcsprm::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 wcsprm::ntab |
(Given) See wcsprm::tab.
| int wcsprm::nwtb |
(Given) See wcsprm::wtb.
| struct tabprm* wcsprm::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* wcsprm::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 wcsprm::lngtyp[8] |
(Returned) Four-character WCS celestial longitude and ...
| char wcsprm::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 wcsprm::lng |
(Returned) Index for the longitude coordinate, and ...
| int wcsprm::lat |
(Returned) ... index for the latitude coordinate, and ...
| int wcsprm::spec |
(Returned) ... index for the spectral coordinate, and ...
| int wcsprm::time |
| int wcsprm::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 wcsprm::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* wcsprm::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):
CUBEFACE). Second digit (i.e. 100s):
STOKES, CUBEFACE). Third digit (i.e. 10s):
The fourth digit is used as a qualifier depending on the axis type.
For celestial axes:
CUBEFACE number. CTYPEia in "4-3" form with unrecognized algorithm code will have its type set to -1 and generate an error.
| struct linprm wcsprm::lin |
(Returned) Linear transformation parameters (usage is described in the prologue to lin.h).
| struct celprm wcsprm::cel |
(Returned) Celestial transformation parameters (usage is described in the prologue to cel.h).
| struct spcprm wcsprm::spc |
(Returned) Spectral transformation parameters (usage is described in the prologue to spc.h).
| struct wcserr* wcsprm::err |
(Returned) If enabled, when an error status is returned, this struct contains detailed information about the error, see wcserr_enable().
| int wcsprm::m_flag |
(For internal use only.)
| int wcsprm::m_naxis |
(For internal use only.)
| double* wcsprm::m_crpix |
(For internal use only.)
| double * wcsprm::m_pc |
(For internal use only.)
| double * wcsprm::m_cdelt |
(For internal use only.)
| double * wcsprm::m_crval |
(For internal use only.)
| char(* wcsprm::m_cunit)[72] |
(For internal use only.)
| char((* wcsprm::m_ctype)[72] |
(For internal use only.)
| struct pvcard* wcsprm::m_pv |
(For internal use only.)
| struct pscard* wcsprm::m_ps |
(For internal use only.)
| double* wcsprm::m_cd |
(For internal use only.)
| double * wcsprm::m_crota |
(For internal use only.)
| int* wcsprm::m_colax |
(For internal use only.)
| char(* wcsprm::m_cname)[72] |
(For internal use only.)
| double* wcsprm::m_crder |
(For internal use only.)
| double * wcsprm::m_csyer |
(For internal use only.)
| double * wcsprm::m_czphs |
(For internal use only.)
| double * wcsprm::m_cperi |
(For internal use only.)
| struct auxprm* wcsprm::m_aux |
| struct tabprm* wcsprm::m_tab |
(For internal use only.)
| struct wtbarr* wcsprm::m_wtb |
(For internal use only.)