1 /*
2 *+
3 * Name:
4 * palEpco
5
6 * Purpose:
7 * Convert an epoch into the appropriate form - 'B' or 'J'
8
9 * Language:
10 * Starlink ANSI C
11
12 * Type of Module:
13 * Library routine
14
15 * Invocation:
16 * double palEpco( char k0, char k, double e );
17
18 * Arguments:
19 * k0 = char (Given)
20 * Form of result: 'B'=Besselian, 'J'=Julian
21 * k = char (Given)
22 * Form of given epoch: 'B' or 'J'.
23
24 * Description:
25 * Converts a Besselian or Julian epoch to a Julian or Besselian
26 * epoch.
27
28 * Authors:
29 * PTW: Patrick T. Wallace
30 * TIMJ: Tim Jenness (JAC, Hawaii)
31 * {enter_new_authors_here}
32
33 * Notes:
34 * - The result is always either equal to or very close to
35 * the given epoch E. The routine is required only in
36 * applications where punctilious treatment of heterogeneous
37 * mixtures of star positions is necessary.
38 * - k and k0 are case insensitive. This differes slightly from the
39 * Fortran SLA implementation.
40 * - k and k0 are not validated. They are interpreted as follows:
41 * o If k0 and k are the same the result is e
42 * o If k0 is 'b' or 'B' and k isn't the conversion is J to B.
43 * o In all other cases, the conversion is B to J.
44
45 * History:
46 * 2012-03-01 (TIMJ):
47 * Initial version. Documentation from SLA/F.
48 * Adapted with permission from the Fortran SLALIB library.
49 * {enter_further_changes_here}
50
51 * Copyright:
52 * Copyright (C) 1995 Rutherford Appleton Laboratory
53 * Copyright (C) 2012 Science and Technology Facilities Council.
54 * All Rights Reserved.
55
56 * Licence:
57 * This program is free software; you can redistribute it and/or
58 * modify it under the terms of the GNU General Public License as
59 * published by the Free Software Foundation; either version 3 of
60 * the License, or (at your option) any later version.
61 *
62 * This program is distributed in the hope that it will be
63 * useful, but WITHOUT ANY WARRANTY; without even the implied
64 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
65 * PURPOSE. See the GNU General Public License for more details.
66 *
67 * You should have received a copy of the GNU General Public License
68 * along with this program; if not, write to the Free Software
69 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301
70 * USA.
71
72 * Bugs:
73 * {note_any_bugs_here}
74 *-
75 */
76
77 #include "pal.h"
78 #include "pal1sofa.h"
79
80 #include <ctype.h>
81
palEpco(char k0,char k,double e)82 double palEpco( char k0, char k, double e ) {
83
84 double new_epoch = 0.0;
85 double djm;
86 double djm0;
87
88 /* Use upper case */
89 k0 = toupper( k0 );
90 k = toupper( k );
91
92 if (k == k0) {
93 new_epoch = e;
94 } else if (k0 == 'B') {
95 eraEpj2jd( e, &djm0, &djm );
96 new_epoch = eraEpb( djm0, djm );
97 } else {
98 eraEpb2jd( e, &djm0, &djm );
99 new_epoch = eraEpj( djm0, djm );
100 }
101 return new_epoch;
102 }
103