source: trunk/FACT++/pal/palDafin.c@ 20115

Last change on this file since 20115 was 18347, checked in by tbretz, 9 years ago
File size: 6.3 KB
Line 
1/*
2*+
3* Name:
4* palDafin
5
6* Purpose:
7* Sexagesimal character string to angle
8
9* Language:
10* Starlink ANSI C
11
12* Type of Module:
13* Library routine
14
15* Invocation:
16* void palDafin ( const char *string, int *ipos, double *a, int *j );
17
18* Arguments:
19* string = const char * (Given)
20* String containing deg, arcmin, arcsec fields
21* ipos = int * (Given & Returned)
22* Position to start decoding "string". First character
23* is position 1 for compatibility with SLA. After
24* calling this routine "iptr" will be positioned after
25* the sexagesimal string.
26* a = double * (Returned)
27* Angle in radians.
28* j = int * (Returned)
29* status: 0 = OK
30* +1 = default, A unchanged
31* -1 = bad degrees )
32* -2 = bad arcminutes ) (note 3)
33* -3 = bad arcseconds )
34
35* Description:
36* Extracts an angle from a sexagesimal string with degrees, arcmin,
37* arcsec fields using space or comma delimiters.
38
39* Authors:
40* TIMJ: Tim Jenness (JAC, Hawaii)
41* PTW: Patrick T. Wallace
42* {enter_new_authors_here}
43
44* Example:
45* argument before after
46*
47* STRING '-57 17 44.806 12 34 56.7' unchanged
48* IPTR 1 16 (points to 12...)
49* A ? -1.00000D0
50* J ? 0
51
52* Notes:
53* - The first three "fields" in STRING are degrees, arcminutes,
54* arcseconds, separated by spaces or commas. The degrees field
55* may be signed, but not the others. The decoding is carried
56* out by the palDfltin routine and is free-format.
57* - Successive fields may be absent, defaulting to zero. For
58* zero status, the only combinations allowed are degrees alone,
59* degrees and arcminutes, and all three fields present. If all
60* three fields are omitted, a status of +1 is returned and A is
61* unchanged. In all other cases A is changed.
62* - Range checking:
63*
64* The degrees field is not range checked. However, it is
65* expected to be integral unless the other two fields are absent.
66*
67* The arcminutes field is expected to be 0-59, and integral if
68* the arcseconds field is present. If the arcseconds field
69* is absent, the arcminutes is expected to be 0-59.9999...
70*
71* The arcseconds field is expected to be 0-59.9999...
72*
73* - Decoding continues even when a check has failed. Under these
74* circumstances the field takes the supplied value, defaulting
75* to zero, and the result A is computed and returned.
76* - Further fields after the three expected ones are not treated
77* as an error. The pointer IPOS is left in the correct state
78* for further decoding with the present routine or with palDfltin
79* etc. See the example, above.
80* - If STRING contains hours, minutes, seconds instead of degrees
81* etc, or if the required units are turns (or days) instead of
82* radians, the result A should be multiplied as follows:
83*
84* for to obtain multiply
85* STRING A in A by
86*
87* d ' " radians 1 = 1.0
88* d ' " turns 1/2pi = 0.1591549430918953358
89* h m s radians 15 = 15.0
90* h m s days 15/2pi = 2.3873241463784300365
91
92* History:
93* 2012-03-08 (TIMJ):
94* Initial version from SLA/F using Fortran documentation
95* Adapted with permission from the Fortran SLALIB library.
96* 2012-10-17 (TIMJ):
97* Fix range check on arcminute value.
98* {enter_further_changes_here}
99
100* Copyright:
101* Copyright (C) 1996 Rutherford Appleton Laboratory
102* Copyright (C) 2012 Science and Technology Facilities Council.
103* All Rights Reserved.
104
105* Licence:
106* This program is free software; you can redistribute it and/or
107* modify it under the terms of the GNU General Public License as
108* published by the Free Software Foundation; either version 3 of
109* the License, or (at your option) any later version.
110*
111* This program is distributed in the hope that it will be
112* useful, but WITHOUT ANY WARRANTY; without even the implied
113* warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
114* PURPOSE. See the GNU General Public License for more details.
115*
116* You should have received a copy of the GNU General Public License
117* along with this program; if not, write to the Free Software
118* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
119* MA 02110-1301, USA.
120
121* Bugs:
122* {note_any_bugs_here}
123*-
124*/
125
126#include "pal.h"
127#include "palmac.h"
128#include "pal1sofa.h"
129
130#include <math.h>
131
132void palDafin ( const char *string, int *ipos, double *a, int *j ) {
133
134 int jd = 0; /* Status for degree parsing */
135 int jm = 0; /* Status for arcmin parsing */
136 int js = 0; /* Status for arcsec parsing */
137 int jf = 0; /* Internal copy of status */
138 double deg = 0.0;
139 double arcmin = 0.0;
140 double arcsec = 0.0;
141
142 /* Decode degrees, arcminutes, arcseconds */
143 palDfltin( string, ipos, &deg, &jd );
144 if (jd > 1) {
145 jf = -1;
146 } else {
147
148 palDfltin( string, ipos, &arcmin, &jm );
149 if ( jm < 0 || jm > 1 ) {
150 jf = -2;
151 } else {
152
153 palDfltin( string, ipos, &arcsec, &js );
154 if (js < 0 || js > 1) {
155 jf = -3;
156
157 } else if (jd > 0) { /* See if combination of fields is credible */
158 /* No degrees: arcmin, arcsec ought also to be absent */
159 if (jm == 0) {
160 /* Suspect arcmin */
161 jf = -2;
162 } else if (js == 0) {
163 /* Suspect arcsec */
164 jf = -3;
165 } else {
166 /* All three fields absent */
167 jf = 1;
168 }
169
170 } else if (jm != 0 && js == 0) { /* Deg present: if arcsec present should have arcmin */
171 jf = -3;
172
173 /* Tests for range and integrality */
174 } else if (jm == 0 && DINT(deg) != deg) { /* Degrees */
175 jf = -1;
176
177 } else if ( (js == 0 && DINT(arcmin) != arcmin) || arcmin >= 60.0 ) { /* Arcmin */
178 jf = -2;
179
180 } else if (arcsec >= 60.0) { /* Arcsec */
181 jf = -3;
182 }
183 }
184 }
185
186 /* Unless all three fields absent, compute angle value */
187 if (jf <= 0) {
188 *a = PAL__DAS2R * ( 60.0 * ( 60.0 * fabs(deg) + arcmin) + arcsec );
189 if ( jd < 0 ) *a *= -1.;
190 }
191
192 *j = jf;
193
194}
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