WCSLIB: spc.h Source File

WCSLIB 7.11

spc.h
Go to the documentation of this file.
1/*============================================================================
2 WCSLIB 7.11 - an implementation of the FITS WCS standard.
3 Copyright (C) 1995-2022, Mark Calabretta
4
5 This file is part of WCSLIB.
6
7 WCSLIB is free software: you can redistribute it and/or modify it under the
8 terms of the GNU Lesser General Public License as published by the Free
9 Software Foundation, either version 3 of the License, or (at your option)
10 any later version.
11
12 WCSLIB is distributed in the hope that it will be useful, but WITHOUT ANY
13 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
14 FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for
15 more details.
16
17 You should have received a copy of the GNU Lesser General Public License
18 along with WCSLIB. If not, see http://www.gnu.org/licenses.
19
20 Author: Mark Calabretta, Australia Telescope National Facility, CSIRO.
21 http://www.atnf.csiro.au/people/Mark.Calabretta
22 $Id: spc.h,v 7.11 2022/04/26 06:13:52 mcalabre Exp $
23*=============================================================================
24*
25* WCSLIB 7.11 - C routines that implement the FITS World Coordinate System
26* (WCS) standard. Refer to the README file provided with WCSLIB for an
27* overview of the library.
28*
29*
30* Summary of the spc routines
31* ---------------------------
32* Routines in this suite implement the part of the FITS World Coordinate
33* System (WCS) standard that deals with spectral coordinates, as described in
34*
35= "Representations of world coordinates in FITS",
36= Greisen, E.W., & Calabretta, M.R. 2002, A&A, 395, 1061 (WCS Paper I)
37=
38= "Representations of spectral coordinates in FITS",
39= Greisen, E.W., Calabretta, M.R., Valdes, F.G., & Allen, S.L.
40= 2006, A&A, 446, 747 (WCS Paper III)
41*
42* These routines define methods to be used for computing spectral world
43* coordinates from intermediate world coordinates (a linear transformation
44* of image pixel coordinates), and vice versa. They are based on the spcprm
45* struct which contains all information needed for the computations. The
46* struct contains some members that must be set by the user, and others that
47* are maintained by these routines, somewhat like a C++ class but with no
48* encapsulation.
49*
50* Routine spcini() is provided to initialize the spcprm struct with default
51* values, spcfree() reclaims any memory that may have been allocated to store
52* an error message, spcsize() computes its total size including allocated
53* memory, and spcprt() prints its contents.
54*
55* spcperr() prints the error message(s) (if any) stored in a spcprm struct.
56*
57* A setup routine, spcset(), computes intermediate values in the spcprm struct
58* from parameters in it that were supplied by the user. The struct always
59* needs to be set up by spcset() but it need not be called explicitly - refer
60* to the explanation of spcprm::flag.
61*
62* spcx2s() and spcs2x() implement the WCS spectral coordinate transformations.
63* In fact, they are high level driver routines for the lower level spectral
64* coordinate transformation routines described in spx.h.
65*
66* A number of routines are provided to aid in analysing or synthesising sets
67* of FITS spectral axis keywords:
68*
69* - spctype() checks a spectral CTYPEia keyword for validity and returns
70* information derived from it.
71*
72* - Spectral keyword analysis routine spcspxe() computes the values of the
73* X-type spectral variables for the S-type variables supplied.
74*
75* - Spectral keyword synthesis routine, spcxpse(), computes the S-type
76* variables for the X-types supplied.
77*
78* - Given a set of spectral keywords, a translation routine, spctrne(),
79* produces the corresponding set for the specified spectral CTYPEia.
80*
81* - spcaips() translates AIPS-convention spectral CTYPEia and VELREF
82* keyvalues.
83*
84* Spectral variable types - S, P, and X:
85* --------------------------------------
86* A few words of explanation are necessary regarding spectral variable types
87* in FITS.
88*
89* Every FITS spectral axis has three associated spectral variables:
90*
91* S-type: the spectral variable in which coordinates are to be
92* expressed. Each S-type is encoded as four characters and is
93* linearly related to one of four basic types as follows:
94*
95* F (Frequency):
96* - 'FREQ': frequency
97* - 'AFRQ': angular frequency
98* - 'ENER': photon energy
99* - 'WAVN': wave number
100* - 'VRAD': radio velocity
101*
102* W (Wavelength in vacuo):
103* - 'WAVE': wavelength
104* - 'VOPT': optical velocity
105* - 'ZOPT': redshift
106*
107* A (wavelength in Air):
108* - 'AWAV': wavelength in air
109*
110* V (Velocity):
111* - 'VELO': relativistic velocity
112* - 'BETA': relativistic beta factor
113*
114* The S-type forms the first four characters of the CTYPEia keyvalue,
115* and CRVALia and CDELTia are expressed as S-type quantities so that
116* they provide a first-order approximation to the S-type variable at
117* the reference point.
118*
119* Note that 'AFRQ', angular frequency, is additional to the variables
120* defined in WCS Paper III.
121*
122* P-type: the basic spectral variable (F, W, A, or V) with which the
123* S-type variable is associated (see list above).
124*
125* For non-grism axes, the P-type is encoded as the eighth character of
126* CTYPEia.
127*
128* X-type: the basic spectral variable (F, W, A, or V) for which the
129* spectral axis is linear, grisms excluded (see below).
130*
131* For non-grism axes, the X-type is encoded as the sixth character of
132* CTYPEia.
133*
134* Grisms: Grism axes have normal S-, and P-types but the axis is linear,
135* not in any spectral variable, but in a special "grism parameter".
136* The X-type spectral variable is either W or A for grisms in vacuo or
137* air respectively, but is encoded as 'w' or 'a' to indicate that an
138* additional transformation is required to convert to or from the
139* grism parameter. The spectral algorithm code for grisms also has a
140* special encoding in CTYPEia, either 'GRI' (in vacuo) or 'GRA' (in air).
141*
142* In the algorithm chain, the non-linear transformation occurs between the
143* X-type and the P-type variables; the transformation between P-type and
144* S-type variables is always linear.
145*
146* When the P-type and X-type variables are the same, the spectral axis is
147* linear in the S-type variable and the second four characters of CTYPEia
148* are blank. This can never happen for grism axes.
149*
150* As an example, correlating radio spectrometers always produce spectra that
151* are regularly gridded in frequency; a redshift scale on such a spectrum is
152* non-linear. The required value of CTYPEia would be 'ZOPT-F2W', where the
153* desired S-type is 'ZOPT' (redshift), the P-type is necessarily 'W'
154* (wavelength), and the X-type is 'F' (frequency) by the nature of the
155* instrument.
156*
157* Air-to-vacuum wavelength conversion:
158* ------------------------------------
159* Please refer to the prologue of spx.h for important comments relating to the
160* air-to-vacuum wavelength conversion.
161*
162* Argument checking:
163* ------------------
164* The input spectral values are only checked for values that would result in
165* floating point exceptions. In particular, negative frequencies and
166* wavelengths are allowed, as are velocities greater than the speed of
167* light. The same is true for the spectral parameters - rest frequency and
168* wavelength.
169*
170* Accuracy:
171* ---------
172* No warranty is given for the accuracy of these routines (refer to the
173* copyright notice); intending users must satisfy for themselves their
174* adequacy for the intended purpose. However, closure effectively to within
175* double precision rounding error was demonstrated by test routine tspc.c
176* which accompanies this software.
177*
178*
179* spcini() - Default constructor for the spcprm struct
180* ----------------------------------------------------
181* spcini() sets all members of a spcprm struct to default values. It should
182* be used to initialize every spcprm struct.
183*
184* PLEASE NOTE: If the spcprm struct has already been initialized, then before
185* reinitializing, it spcfree() should be used to free any memory that may have
186* been allocated to store an error message. A memory leak may otherwise
187* result.
188*
189* Given and returned:
190* spc struct spcprm*
191* Spectral transformation parameters.
192*
193* Function return value:
194* int Status return value:
195* 0: Success.
196* 1: Null spcprm pointer passed.
197*
198*
199* spcfree() - Destructor for the spcprm struct
200* --------------------------------------------
201* spcfree() frees any memory that may have been allocated to store an error
202* message in the spcprm struct.
203*
204* Given:
205* spc struct spcprm*
206* Spectral transformation parameters.
207*
208* Function return value:
209* int Status return value:
210* 0: Success.
211* 1: Null spcprm pointer passed.
212*
213*
214* spcsize() - Compute the size of a spcprm struct
215* -----------------------------------------------
216* spcsize() computes the full size of a spcprm struct, including allocated
217* memory.
218*
219* Given:
220* spc const struct spcprm*
221* Spectral transformation parameters.
222*
223* If NULL, the base size of the struct and the allocated
224* size are both set to zero.
225*
226* Returned:
227* sizes int[2] The first element is the base size of the struct as
228* returned by sizeof(struct spcprm). The second element
229* is the total allocated size, in bytes. This figure
230* includes memory allocated for the constituent struct,
231* spcprm::err.
232*
233* It is not an error for the struct not to have been set
234* up via spcset().
235*
236* Function return value:
237* int Status return value:
238* 0: Success.
239*
240*
241* spcprt() - Print routine for the spcprm struct
242* ----------------------------------------------
243* spcprt() prints the contents of a spcprm struct using wcsprintf(). Mainly
244* intended for diagnostic purposes.
245*
246* Given:
247* spc const struct spcprm*
248* Spectral transformation parameters.
249*
250* Function return value:
251* int Status return value:
252* 0: Success.
253* 1: Null spcprm pointer passed.
254*
255*
256* spcperr() - Print error messages from a spcprm struct
257* -----------------------------------------------------
258* spcperr() prints the error message(s) (if any) stored in a spcprm struct.
259* If there are no errors then nothing is printed. It uses wcserr_prt(), q.v.
260*
261* Given:
262* spc const struct spcprm*
263* Spectral transformation parameters.
264*
265* prefix const char *
266* If non-NULL, each output line will be prefixed with
267* this string.
268*
269* Function return value:
270* int Status return value:
271* 0: Success.
272* 1: Null spcprm pointer passed.
273*
274*
275* spcset() - Setup routine for the spcprm struct
276* ----------------------------------------------
277* spcset() sets up a spcprm struct according to information supplied within
278* it.
279*
280* Note that this routine need not be called directly; it will be invoked by
281* spcx2s() and spcs2x() if spcprm::flag is anything other than a predefined
282* magic value.
283*
284* Given and returned:
285* spc struct spcprm*
286* Spectral transformation parameters.
287*
288* Function return value:
289* int Status return value:
290* 0: Success.
291* 1: Null spcprm pointer passed.
292* 2: Invalid spectral parameters.
293*
294* For returns > 1, a detailed error message is set in
295* spcprm::err if enabled, see wcserr_enable().
296*
297*
298* spcx2s() - Transform to spectral coordinates
299* --------------------------------------------
300* spcx2s() transforms intermediate world coordinates to spectral coordinates.
301*
302* Given and returned:
303* spc struct spcprm*
304* Spectral transformation parameters.
305*
306* Given:
307* nx int Vector length.
308*
309* sx int Vector stride.
310*
311* sspec int Vector stride.
312*
313* x const double[]
314* Intermediate world coordinates, in SI units.
315*
316* Returned:
317* spec double[] Spectral coordinates, in SI units.
318*
319* stat int[] Status return value status for each vector element:
320* 0: Success.
321* 1: Invalid value of x.
322*
323* Function return value:
324* int Status return value:
325* 0: Success.
326* 1: Null spcprm pointer passed.
327* 2: Invalid spectral parameters.
328* 3: One or more of the x coordinates were invalid,
329* as indicated by the stat vector.
330*
331* For returns > 1, a detailed error message is set in
332* spcprm::err if enabled, see wcserr_enable().
333*
334*
335* spcs2x() - Transform spectral coordinates
336* -----------------------------------------
337* spcs2x() transforms spectral world coordinates to intermediate world
338* coordinates.
339*
340* Given and returned:
341* spc struct spcprm*
342* Spectral transformation parameters.
343*
344* Given:
345* nspec int Vector length.
346*
347* sspec int Vector stride.
348*
349* sx int Vector stride.
350*
351* spec const double[]
352* Spectral coordinates, in SI units.
353*
354* Returned:
355* x double[] Intermediate world coordinates, in SI units.
356*
357* stat int[] Status return value status for each vector element:
358* 0: Success.
359* 1: Invalid value of spec.
360*
361* Function return value:
362* int Status return value:
363* 0: Success.
364* 1: Null spcprm pointer passed.
365* 2: Invalid spectral parameters.
366* 4: One or more of the spec coordinates were
367* invalid, as indicated by the stat vector.
368*
369* For returns > 1, a detailed error message is set in
370* spcprm::err if enabled, see wcserr_enable().
371*
372*
373* spctype() - Spectral CTYPEia keyword analysis
374* ---------------------------------------------
375* spctype() checks whether a CTYPEia keyvalue is a valid spectral axis type
376* and if so returns information derived from it relating to the associated S-,
377* P-, and X-type spectral variables (see explanation above).
378*
379* The return arguments are guaranteed not be modified if CTYPEia is not a
380* valid spectral type; zero-pointers may be specified for any that are not of
381* interest.
382*
383* A deprecated form of this function, spctyp(), lacks the wcserr** parameter.
384*
385* Given:
386* ctype const char[9]
387* The CTYPEia keyvalue, (eight characters with null
388* termination).
389*
390* Returned:
391* stype char[] The four-letter name of the S-type spectral variable
392* copied or translated from ctype. If a non-zero
393* pointer is given, the array must accomodate a null-
394* terminated string of length 5.
395*
396* scode char[] The three-letter spectral algorithm code copied or
397* translated from ctype. Logarithmic ('LOG') and
398* tabular ('TAB') codes are also recognized. If a
399* non-zero pointer is given, the array must accomodate a
400* null-terminated string of length 4.
401*
402* sname char[] Descriptive name of the S-type spectral variable.
403* If a non-zero pointer is given, the array must
404* accomodate a null-terminated string of length 22.
405*
406* units char[] SI units of the S-type spectral variable. If a
407* non-zero pointer is given, the array must accomodate a
408* null-terminated string of length 8.
409*
410* ptype char* Character code for the P-type spectral variable
411* derived from ctype, one of 'F', 'W', 'A', or 'V'.
412*
413* xtype char* Character code for the X-type spectral variable
414* derived from ctype, one of 'F', 'W', 'A', or 'V'.
415* Also, 'w' and 'a' are synonymous to 'W' and 'A' for
416* grisms in vacuo and air respectively. Set to 'L' or
417* 'T' for logarithmic ('LOG') and tabular ('TAB') axes.
418*
419* restreq int* Multivalued flag that indicates whether rest
420* frequency or wavelength is required to compute
421* spectral variables for this CTYPEia:
422* 0: Not required.
423* 1: Required for the conversion between S- and
424* P-types (e.g. 'ZOPT-F2W').
425* 2: Required for the conversion between P- and
426* X-types (e.g. 'BETA-W2V').
427* 3: Required for the conversion between S- and
428* P-types, and between P- and X-types, but not
429* between S- and X-types (this applies only for
430* 'VRAD-V2F', 'VOPT-V2W', and 'ZOPT-V2W').
431* Thus the rest frequency or wavelength is required for
432* spectral coordinate computations (i.e. between S- and
433* X-types) only if restreq%3 != 0.
434*
435* err struct wcserr **
436* If enabled, for function return values > 1, this
437* struct will contain a detailed error message, see
438* wcserr_enable(). May be NULL if an error message is
439* not desired. Otherwise, the user is responsible for
440* deleting the memory allocated for the wcserr struct.
441*
442* Function return value:
443* int Status return value:
444* 0: Success.
445* 2: Invalid spectral parameters (not a spectral
446* CTYPEia).
447*
448*
449* spcspxe() - Spectral keyword analysis
450* ------------------------------------
451* spcspxe() analyses the CTYPEia and CRVALia FITS spectral axis keyword values
452* and returns information about the associated X-type spectral variable.
453*
454* A deprecated form of this function, spcspx(), lacks the wcserr** parameter.
455*
456* Given:
457* ctypeS const char[9]
458* Spectral axis type, i.e. the CTYPEia keyvalue, (eight
459* characters with null termination). For non-grism
460* axes, the character code for the P-type spectral
461* variable in the algorithm code (i.e. the eighth
462* character of CTYPEia) may be set to '?' (it will not
463* be reset).
464*
465* crvalS double Value of the S-type spectral variable at the reference
466* point, i.e. the CRVALia keyvalue, SI units.
467*
468* restfrq,
469* restwav double Rest frequency [Hz] and rest wavelength in vacuo [m],
470* only one of which need be given, the other should be
471* set to zero.
472*
473* Returned:
474* ptype char* Character code for the P-type spectral variable
475* derived from ctypeS, one of 'F', 'W', 'A', or 'V'.
476*
477* xtype char* Character code for the X-type spectral variable
478* derived from ctypeS, one of 'F', 'W', 'A', or 'V'.
479* Also, 'w' and 'a' are synonymous to 'W' and 'A' for
480* grisms in vacuo and air respectively; crvalX and dXdS
481* (see below) will conform to these.
482*
483* restreq int* Multivalued flag that indicates whether rest frequency
484* or wavelength is required to compute spectral
485* variables for this CTYPEia, as for spctype().
486*
487* crvalX double* Value of the X-type spectral variable at the reference
488* point, SI units.
489*
490* dXdS double* The derivative, dX/dS, evaluated at the reference
491* point, SI units. Multiply the CDELTia keyvalue by
492* this to get the pixel spacing in the X-type spectral
493* coordinate.
494*
495* err struct wcserr **
496* If enabled, for function return values > 1, this
497* struct will contain a detailed error message, see
498* wcserr_enable(). May be NULL if an error message is
499* not desired. Otherwise, the user is responsible for
500* deleting the memory allocated for the wcserr struct.
501*
502* Function return value:
503* int Status return value:
504* 0: Success.
505* 2: Invalid spectral parameters.
506*
507*
508* spcxpse() - Spectral keyword synthesis
509* -------------------------------------
510* spcxpse(), for the spectral axis type specified and the value provided for
511* the X-type spectral variable at the reference point, deduces the value of
512* the FITS spectral axis keyword CRVALia and also the derivative dS/dX which
513* may be used to compute CDELTia. See above for an explanation of the S-,
514* P-, and X-type spectral variables.
515*
516* A deprecated form of this function, spcxps(), lacks the wcserr** parameter.
517*
518* Given:
519* ctypeS const char[9]
520* The required spectral axis type, i.e. the CTYPEia
521* keyvalue, (eight characters with null termination).
522* For non-grism axes, the character code for the P-type
523* spectral variable in the algorithm code (i.e. the
524* eighth character of CTYPEia) may be set to '?' (it
525* will not be reset).
526*
527* crvalX double Value of the X-type spectral variable at the reference
528* point (N.B. NOT the CRVALia keyvalue), SI units.
529*
530* restfrq,
531* restwav double Rest frequency [Hz] and rest wavelength in vacuo [m],
532* only one of which need be given, the other should be
533* set to zero.
534*
535* Returned:
536* ptype char* Character code for the P-type spectral variable
537* derived from ctypeS, one of 'F', 'W', 'A', or 'V'.
538*
539* xtype char* Character code for the X-type spectral variable
540* derived from ctypeS, one of 'F', 'W', 'A', or 'V'.
541* Also, 'w' and 'a' are synonymous to 'W' and 'A' for
542* grisms; crvalX and cdeltX must conform to these.
543*
544* restreq int* Multivalued flag that indicates whether rest frequency
545* or wavelength is required to compute spectral
546* variables for this CTYPEia, as for spctype().
547*
548* crvalS double* Value of the S-type spectral variable at the reference
549* point (i.e. the appropriate CRVALia keyvalue), SI
550* units.
551*
552* dSdX double* The derivative, dS/dX, evaluated at the reference
553* point, SI units. Multiply this by the pixel spacing
554* in the X-type spectral coordinate to get the CDELTia
555* keyvalue.
556*
557* err struct wcserr **
558* If enabled, for function return values > 1, this
559* struct will contain a detailed error message, see
560* wcserr_enable(). May be NULL if an error message is
561* not desired. Otherwise, the user is responsible for
562* deleting the memory allocated for the wcserr struct.
563*
564* Function return value:
565* int Status return value:
566* 0: Success.
567* 2: Invalid spectral parameters.
568*
569*
570* spctrne() - Spectral keyword translation
571* ---------------------------------------
572* spctrne() translates a set of FITS spectral axis keywords into the
573* corresponding set for the specified spectral axis type. For example, a
574* 'FREQ' axis may be translated into 'ZOPT-F2W' and vice versa.
575*
576* A deprecated form of this function, spctrn(), lacks the wcserr** parameter.
577*
578* Given:
579* ctypeS1 const char[9]
580* Spectral axis type, i.e. the CTYPEia keyvalue, (eight
581* characters with null termination). For non-grism
582* axes, the character code for the P-type spectral
583* variable in the algorithm code (i.e. the eighth
584* character of CTYPEia) may be set to '?' (it will not
585* be reset).
586*
587* crvalS1 double Value of the S-type spectral variable at the reference
588* point, i.e. the CRVALia keyvalue, SI units.
589*
590* cdeltS1 double Increment of the S-type spectral variable at the
591* reference point, SI units.
592*
593* restfrq,
594* restwav double Rest frequency [Hz] and rest wavelength in vacuo [m],
595* only one of which need be given, the other should be
596* set to zero. Neither are required if the translation
597* is between wave-characteristic types, or between
598* velocity-characteristic types. E.g., required for
599* 'FREQ' -> 'ZOPT-F2W', but not required for
600* 'VELO-F2V' -> 'ZOPT-F2W'.
601*
602* Given and returned:
603* ctypeS2 char[9] Required spectral axis type (eight characters with
604* null termination). The first four characters are
605* required to be given and are never modified. The
606* remaining four, the algorithm code, are completely
607* determined by, and must be consistent with, ctypeS1
608* and the first four characters of ctypeS2. A non-zero
609* status value will be returned if they are inconsistent
610* (see below). However, if the final three characters
611* are specified as "???", or if just the eighth
612* character is specified as '?', the correct algorithm
613* code will be substituted (applies for grism axes as
614* well as non-grism).
615*
616* Returned:
617* crvalS2 double* Value of the new S-type spectral variable at the
618* reference point, i.e. the new CRVALia keyvalue, SI
619* units.
620*
621* cdeltS2 double* Increment of the new S-type spectral variable at the
622* reference point, i.e. the new CDELTia keyvalue, SI
623* units.
624*
625* err struct wcserr **
626* If enabled, for function return values > 1, this
627* struct will contain a detailed error message, see
628* wcserr_enable(). May be NULL if an error message is
629* not desired. Otherwise, the user is responsible for
630* deleting the memory allocated for the wcserr struct.
631*
632* Function return value:
633* int Status return value:
634* 0: Success.
635* 2: Invalid spectral parameters.
636*
637* A status value of 2 will be returned if restfrq or
638* restwav are not specified when required, or if ctypeS1
639* or ctypeS2 are self-inconsistent, or have different
640* spectral X-type variables.
641*
642*
643* spcaips() - Translate AIPS-convention spectral keywords
644* -------------------------------------------------------
645* spcaips() translates AIPS-convention spectral CTYPEia and VELREF keyvalues.
646*
647* Given:
648* ctypeA const char[9]
649* CTYPEia keyvalue possibly containing an
650* AIPS-convention spectral code (eight characters, need
651* not be null-terminated).
652*
653* velref int AIPS-convention VELREF code. It has the following
654* integer values:
655* 1: LSR kinematic, originally described simply as
656* "LSR" without distinction between the kinematic
657* and dynamic definitions.
658* 2: Barycentric, originally described as "HEL"
659* meaning heliocentric.
660* 3: Topocentric, originally described as "OBS"
661* meaning geocentric but widely interpreted as
662* topocentric.
663* AIPS++ extensions to VELREF are also recognized:
664* 4: LSR dynamic.
665* 5: Geocentric.
666* 6: Source rest frame.
667* 7: Galactocentric.
668*
669* For an AIPS 'VELO' axis, a radio convention velocity
670* (VRAD) is denoted by adding 256 to VELREF, otherwise
671* an optical velocity (VOPT) is indicated (this is not
672* applicable to 'FREQ' or 'FELO' axes). Setting velref
673* to 0 or 256 chooses between optical and radio velocity
674* without specifying a Doppler frame, provided that a
675* frame is encoded in ctypeA. If not, i.e. for
676* ctypeA = 'VELO', ctype will be returned as 'VELO'.
677*
678* VELREF takes precedence over CTYPEia in defining the
679* Doppler frame, e.g.
680*
681= ctypeA = 'VELO-HEL'
682= velref = 1
683*
684* returns ctype = 'VOPT' with specsys set to 'LSRK'.
685*
686* If omitted from the header, the default value of
687* VELREF is 0.
688*
689* Returned:
690* ctype char[9] Translated CTYPEia keyvalue, or a copy of ctypeA if no
691* translation was performed (in which case any trailing
692* blanks in ctypeA will be replaced with nulls).
693*
694* specsys char[9] Doppler reference frame indicated by VELREF or else
695* by CTYPEia with value corresponding to the SPECSYS
696* keyvalue in the FITS WCS standard. May be returned
697* blank if neither specifies a Doppler frame, e.g.
698* ctypeA = 'FELO' and velref%256 == 0.
699*
700* Function return value:
701* int Status return value:
702* -1: No translation required (not an error).
703* 0: Success.
704* 2: Invalid value of VELREF.
705*
706*
707* spcprm struct - Spectral transformation parameters
708* --------------------------------------------------
709* The spcprm struct contains information required to transform spectral
710* coordinates. It consists of certain members that must be set by the user
711* ("given") and others that are set by the WCSLIB routines ("returned"). Some
712* of the latter are supplied for informational purposes while others are for
713* internal use only.
714*
715* int flag
716* (Given and returned) This flag must be set to zero whenever any of the
717* following spcprm structure members are set or changed:
718*
719* - spcprm::type,
720* - spcprm::code,
721* - spcprm::crval,
722* - spcprm::restfrq,
723* - spcprm::restwav,
724* - spcprm::pv[].
725*
726* This signals the initialization routine, spcset(), to recompute the
727* returned members of the spcprm struct. spcset() will reset flag to
728* indicate that this has been done.
729*
730* char type[8]
731* (Given) Four-letter spectral variable type, e.g "ZOPT" for
732* CTYPEia = 'ZOPT-F2W'. (Declared as char[8] for alignment reasons.)
733*
734* char code[4]
735* (Given) Three-letter spectral algorithm code, e.g "F2W" for
736* CTYPEia = 'ZOPT-F2W'.
737*
738* double crval
739* (Given) Reference value (CRVALia), SI units.
740*
741* double restfrq
742* (Given) The rest frequency [Hz], and ...
743*
744* double restwav
745* (Given) ... the rest wavelength in vacuo [m], only one of which need be
746* given, the other should be set to zero. Neither are required if the
747* X and S spectral variables are both wave-characteristic, or both
748* velocity-characteristic, types.
749*
750* double pv[7]
751* (Given) Grism parameters for 'GRI' and 'GRA' algorithm codes:
752* - 0: G, grating ruling density.
753* - 1: m, interference order.
754* - 2: alpha, angle of incidence [deg].
755* - 3: n_r, refractive index at the reference wavelength, lambda_r.
756* - 4: n'_r, dn/dlambda at the reference wavelength, lambda_r (/m).
757* - 5: epsilon, grating tilt angle [deg].
758* - 6: theta, detector tilt angle [deg].
759*
760* The remaining members of the spcprm struct are maintained by spcset() and
761* must not be modified elsewhere:
762*
763* double w[6]
764* (Returned) Intermediate values:
765* - 0: Rest frequency or wavelength (SI).
766* - 1: The value of the X-type spectral variable at the reference point
767* (SI units).
768* - 2: dX/dS at the reference point (SI units).
769* The remainder are grism intermediates.
770*
771* int isGrism
772* (Returned) Grism coordinates?
773* - 0: no,
774* - 1: in vacuum,
775* - 2: in air.
776*
777* int padding1
778* (An unused variable inserted for alignment purposes only.)
779*
780* struct wcserr *err
781* (Returned) If enabled, when an error status is returned, this struct
782* contains detailed information about the error, see wcserr_enable().
783*
784* void *padding2
785* (An unused variable inserted for alignment purposes only.)
786* int (*spxX2P)(SPX_ARGS)
787* (Returned) The first and ...
788* int (*spxP2S)(SPX_ARGS)
789* (Returned) ... the second of the pointers to the transformation
790* functions in the two-step algorithm chain X -> P -> S in the
791* pixel-to-spectral direction where the non-linear transformation is from
792* X to P. The argument list, SPX_ARGS, is defined in spx.h.
793*
794* int (*spxS2P)(SPX_ARGS)
795* (Returned) The first and ...
796* int (*spxP2X)(SPX_ARGS)
797* (Returned) ... the second of the pointers to the transformation
798* functions in the two-step algorithm chain S -> P -> X in the
799* spectral-to-pixel direction where the non-linear transformation is from
800* P to X. The argument list, SPX_ARGS, is defined in spx.h.
801*
802*
803* Global variable: const char *spc_errmsg[] - Status return messages
804* ------------------------------------------------------------------
805* Error messages to match the status value returned from each function.
806*
807*===========================================================================*/
808
809#ifndef WCSLIB_SPC
810#define WCSLIB_SPC
811
812#include "spx.h"
813
814#ifdef __cplusplus
815extern "C" {
816#endif
817
818
819extern const char *spc_errmsg[];
820
821 enum spc_errmsg_enum {
822 SPCERR_NO_CHANGE = -1, // No change.
823 SPCERR_SUCCESS = 0, // Success.
824 SPCERR_NULL_POINTER = 1, // Null spcprm pointer passed.
825 SPCERR_BAD_SPEC_PARAMS = 2, // Invalid spectral parameters.
826 SPCERR_BAD_X = 3, // One or more of x coordinates were
827 // invalid.
828 SPCERR_BAD_SPEC = 4 // One or more of the spec coordinates were
829 // invalid.
830};
831
832 struct spcprm {
833 // Initialization flag (see the prologue above).
834 //--------------------------------------------------------------------------
835 int flag; // Set to zero to force initialization.
836
837 // Parameters to be provided (see the prologue above).
838 //--------------------------------------------------------------------------
839 char type[8]; // Four-letter spectral variable type.
840 char code[4]; // Three-letter spectral algorithm code.
841
842 double crval; // Reference value (CRVALia), SI units.
843 double restfrq; // Rest frequency, Hz.
844 double restwav; // Rest wavelength, m.
845
846 double pv[7]; // Grism parameters:
847 // 0: G, grating ruling density.
848 // 1: m, interference order.
849 // 2: alpha, angle of incidence.
850 // 3: n_r, refractive index at lambda_r.
851 // 4: n'_r, dn/dlambda at lambda_r.
852 // 5: epsilon, grating tilt angle.
853 // 6: theta, detector tilt angle.
854
855 // Information derived from the parameters supplied.
856 //--------------------------------------------------------------------------
857 double w[6]; // Intermediate values.
858 // 0: Rest frequency or wavelength (SI).
859 // 1: CRVALX (SI units).
860 // 2: CDELTX/CDELTia = dX/dS (SI units).
861 // The remainder are grism intermediates.
862
863 int isGrism; // Grism coordinates? 1: vacuum, 2: air.
864 int padding1; // (Dummy inserted for alignment purposes.)
865
866 // Error handling
867 //--------------------------------------------------------------------------
868 struct wcserr *err;
869
870 // Private
871 //--------------------------------------------------------------------------
872 void *padding2; // (Dummy inserted for alignment purposes.)
873 int (*spxX2P)(SPX_ARGS); // Pointers to the transformation functions
874 int (*spxP2S)(SPX_ARGS); // in the two-step algorithm chain in the
875 // pixel-to-spectral direction.
876
877 int (*spxS2P)(SPX_ARGS); // Pointers to the transformation functions
878 int (*spxP2X)(SPX_ARGS); // in the two-step algorithm chain in the
879 // spectral-to-pixel direction.
880};
881
882// Size of the spcprm struct in int units, used by the Fortran wrappers.
883#define SPCLEN (sizeof(struct spcprm)/sizeof(int))
884
885
886 int spcini(struct spcprm *spc);
887
888 int spcfree(struct spcprm *spc);
889
890 int spcsize(const struct spcprm *spc, int sizes[2]);
891
892 int spcprt(const struct spcprm *spc);
893
894 int spcperr(const struct spcprm *spc, const char *prefix);
895
896 int spcset(struct spcprm *spc);
897
898 int spcx2s(struct spcprm *spc, int nx, int sx, int sspec,
899 const double x[], double spec[], int stat[]);
900
901 int spcs2x(struct spcprm *spc, int nspec, int sspec, int sx,
902 const double spec[], double x[], int stat[]);
903
904 int spctype(const char ctype[9], char stype[], char scode[], char sname[],
905 char units[], char *ptype, char *xtype, int *restreq,
906 struct wcserr **err);
907
908 int spcspxe(const char ctypeS[9], double crvalS, double restfrq,
909 double restwav, char *ptype, char *xtype, int *restreq,
910 double *crvalX, double *dXdS, struct wcserr **err);
911
912 int spcxpse(const char ctypeS[9], double crvalX, double restfrq,
913 double restwav, char *ptype, char *xtype, int *restreq,
914 double *crvalS, double *dSdX, struct wcserr **err);
915
916 int spctrne(const char ctypeS1[9], double crvalS1, double cdeltS1,
917 double restfrq, double restwav, char ctypeS2[9], double *crvalS2,
918 double *cdeltS2, struct wcserr **err);
919
920 int spcaips(const char ctypeA[9], int velref, char ctype[9], char specsys[9]);
921
922
923// Deprecated.
924#define spcini_errmsg spc_errmsg
925#define spcprt_errmsg spc_errmsg
926#define spcset_errmsg spc_errmsg
927#define spcx2s_errmsg spc_errmsg
928#define spcs2x_errmsg spc_errmsg
929
930 int spctyp(const char ctype[9], char stype[], char scode[], char sname[],
931 char units[], char *ptype, char *xtype, int *restreq);
932 int spcspx(const char ctypeS[9], double crvalS, double restfrq,
933 double restwav, char *ptype, char *xtype, int *restreq,
934 double *crvalX, double *dXdS);
935 int spcxps(const char ctypeS[9], double crvalX, double restfrq,
936 double restwav, char *ptype, char *xtype, int *restreq,
937 double *crvalS, double *dSdX);
938 int spctrn(const char ctypeS1[9], double crvalS1, double cdeltS1,
939 double restfrq, double restwav, char ctypeS2[9], double *crvalS2,
940 double *cdeltS2);
941
942#ifdef __cplusplus
943}
944#endif
945
946#endif // WCSLIB_SPC
spcspxe
int spcspxe(const char ctypeS[9], double crvalS, double restfrq, double restwav, char *ptype, char *xtype, int *restreq, double *crvalX, double *dXdS, struct wcserr **err)
Spectral keyword analysis.
spcsize
int spcsize(const struct spcprm *spc, int sizes[2])
Compute the size of a spcprm struct.
spcfree
int spcfree(struct spcprm *spc)
Destructor for the spcprm struct.
spcini
int spcini(struct spcprm *spc)
Default constructor for the spcprm struct.
spcperr
int spcperr(const struct spcprm *spc, const char *prefix)
Print error messages from a spcprm struct.
spctrn
int spctrn(const char ctypeS1[9], double crvalS1, double cdeltS1, double restfrq, double restwav, char ctypeS2[9], double *crvalS2, double *cdeltS2)
spc_errmsg_enum
spc_errmsg_enum
Definition: spc.h:821
SPCERR_BAD_SPEC_PARAMS
@ SPCERR_BAD_SPEC_PARAMS
Definition: spc.h:825
SPCERR_SUCCESS
@ SPCERR_SUCCESS
Definition: spc.h:823
SPCERR_BAD_X
@ SPCERR_BAD_X
Definition: spc.h:826
SPCERR_NULL_POINTER
@ SPCERR_NULL_POINTER
Definition: spc.h:824
SPCERR_BAD_SPEC
@ SPCERR_BAD_SPEC
Definition: spc.h:828
SPCERR_NO_CHANGE
@ SPCERR_NO_CHANGE
Definition: spc.h:822
spctrne
int spctrne(const char ctypeS1[9], double crvalS1, double cdeltS1, double restfrq, double restwav, char ctypeS2[9], double *crvalS2, double *cdeltS2, struct wcserr **err)
Spectral keyword translation.
spcspx
int spcspx(const char ctypeS[9], double crvalS, double restfrq, double restwav, char *ptype, char *xtype, int *restreq, double *crvalX, double *dXdS)
spcprt
int spcprt(const struct spcprm *spc)
Print routine for the spcprm struct.
spc_errmsg
const char * spc_errmsg[]
Status return messages.
spcxps
int spcxps(const char ctypeS[9], double crvalX, double restfrq, double restwav, char *ptype, char *xtype, int *restreq, double *crvalS, double *dSdX)
spctyp
int spctyp(const char ctype[9], char stype[], char scode[], char sname[], char units[], char *ptype, char *xtype, int *restreq)
spcaips
int spcaips(const char ctypeA[9], int velref, char ctype[9], char specsys[9])
Translate AIPS-convention spectral keywords.
spcs2x
int spcs2x(struct spcprm *spc, int nspec, int sspec, int sx, const double spec[], double x[], int stat[])
Transform spectral coordinates.
spcx2s
int spcx2s(struct spcprm *spc, int nx, int sx, int sspec, const double x[], double spec[], int stat[])
Transform to spectral coordinates.
spctype
int spctype(const char ctype[9], char stype[], char scode[], char sname[], char units[], char *ptype, char *xtype, int *restreq, struct wcserr **err)
Spectral CTYPEia keyword analysis.
spcset
int spcset(struct spcprm *spc)
Setup routine for the spcprm struct.
spcxpse
int spcxpse(const char ctypeS[9], double crvalX, double restfrq, double restwav, char *ptype, char *xtype, int *restreq, double *crvalS, double *dSdX, struct wcserr **err)
Spectral keyword synthesis.
spx.h
SPX_ARGS
#define SPX_ARGS
For use in declaring spectral conversion function prototypes.
Definition: spx.h:540
spcprm
Spectral transformation parameters.
Definition: spc.h:832
spcprm::spxX2P
int(* spxX2P)(SPX_ARGS)
Definition: spc.h:873
spcprm::crval
double crval
Definition: spc.h:842
spcprm::type
char type[8]
Definition: spc.h:839
spcprm::restwav
double restwav
Definition: spc.h:844
spcprm::code
char code[4]
Definition: spc.h:840
spcprm::spxP2X
int(* spxP2X)(SPX_ARGS)
Definition: spc.h:878
spcprm::err
struct wcserr * err
Definition: spc.h:868
spcprm::restfrq
double restfrq
Definition: spc.h:843
spcprm::padding1
int padding1
Definition: spc.h:864
spcprm::w
double w[6]
Definition: spc.h:857
spcprm::padding2
void * padding2
Definition: spc.h:872
spcprm::spxP2S
int(* spxP2S)(SPX_ARGS)
Definition: spc.h:874
spcprm::pv
double pv[7]
Definition: spc.h:846
spcprm::isGrism
int isGrism
Definition: spc.h:863
spcprm::spxS2P
int(* spxS2P)(SPX_ARGS)
Definition: spc.h:877
spcprm::flag
int flag
Definition: spc.h:835
wcserr
Error message handling.
Definition: wcserr.h:243