FACT++  1.0
eform.c
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1 #include "erfa.h"
2 
3 int eraEform ( int n, double *a, double *f )
4 /*
5 ** - - - - - - - - -
6 ** e r a E f o r m
7 ** - - - - - - - - -
8 **
9 ** Earth reference ellipsoids.
10 **
11 ** Given:
12 ** n int ellipsoid identifier (Note 1)
13 **
14 ** Returned:
15 ** a double equatorial radius (meters, Note 2)
16 ** f double flattening (Note 2)
17 **
18 ** Returned (function value):
19 ** int status: 0 = OK
20 ** -1 = illegal identifier (Note 3)
21 **
22 ** Notes:
23 **
24 ** 1) The identifier n is a number that specifies the choice of
25 ** reference ellipsoid. The following are supported:
26 **
27 ** n ellipsoid
28 **
29 ** 1 ERFA_WGS84
30 ** 2 ERFA_GRS80
31 ** 3 ERFA_WGS72
32 **
33 ** The n value has no significance outside the ERFA software. For
34 ** convenience, symbols ERFA_WGS84 etc. are defined in erfam.h.
35 **
36 ** 2) The ellipsoid parameters are returned in the form of equatorial
37 ** radius in meters (a) and flattening (f). The latter is a number
38 ** around 0.00335, i.e. around 1/298.
39 **
40 ** 3) For the case where an unsupported n value is supplied, zero a and
41 ** f are returned, as well as error status.
42 **
43 ** References:
44 **
45 ** Department of Defense World Geodetic System 1984, National
46 ** Imagery and Mapping Agency Technical Report 8350.2, Third
47 ** Edition, p3-2.
48 **
49 ** Moritz, H., Bull. Geodesique 66-2, 187 (1992).
50 **
51 ** The Department of Defense World Geodetic System 1972, World
52 ** Geodetic System Committee, May 1974.
53 **
54 ** Explanatory Supplement to the Astronomical Almanac,
55 ** P. Kenneth Seidelmann (ed), University Science Books (1992),
56 ** p220.
57 **
58 ** Copyright (C) 2013-2015, NumFOCUS Foundation.
59 ** Derived, with permission, from the SOFA library. See notes at end of file.
60 */
61 {
62 
63 /* Look up a and f for the specified reference ellipsoid. */
64  switch ( n ) {
65 
66  case ERFA_WGS84:
67  *a = 6378137.0;
68  *f = 1.0 / 298.257223563;
69  break;
70 
71  case ERFA_GRS80:
72  *a = 6378137.0;
73  *f = 1.0 / 298.257222101;
74  break;
75 
76  case ERFA_WGS72:
77  *a = 6378135.0;
78  *f = 1.0 / 298.26;
79  break;
80 
81  default:
82 
83  /* Invalid identifier. */
84  *a = 0.0;
85  *f = 0.0;
86  return -1;
87 
88  }
89 
90 /* OK status. */
91  return 0;
92 
93 }
94 /*----------------------------------------------------------------------
95 **
96 **
97 ** Copyright (C) 2013-2015, NumFOCUS Foundation.
98 ** All rights reserved.
99 **
100 ** This library is derived, with permission, from the International
101 ** Astronomical Union's "Standards of Fundamental Astronomy" library,
102 ** available from http://www.iausofa.org.
103 **
104 ** The ERFA version is intended to retain identical functionality to
105 ** the SOFA library, but made distinct through different function and
106 ** file names, as set out in the SOFA license conditions. The SOFA
107 ** original has a role as a reference standard for the IAU and IERS,
108 ** and consequently redistribution is permitted only in its unaltered
109 ** state. The ERFA version is not subject to this restriction and
110 ** therefore can be included in distributions which do not support the
111 ** concept of "read only" software.
112 **
113 ** Although the intent is to replicate the SOFA API (other than
114 ** replacement of prefix names) and results (with the exception of
115 ** bugs; any that are discovered will be fixed), SOFA is not
116 ** responsible for any errors found in this version of the library.
117 **
118 ** If you wish to acknowledge the SOFA heritage, please acknowledge
119 ** that you are using a library derived from SOFA, rather than SOFA
120 ** itself.
121 **
122 **
123 ** TERMS AND CONDITIONS
124 **
125 ** Redistribution and use in source and binary forms, with or without
126 ** modification, are permitted provided that the following conditions
127 ** are met:
128 **
129 ** 1 Redistributions of source code must retain the above copyright
130 ** notice, this list of conditions and the following disclaimer.
131 **
132 ** 2 Redistributions in binary form must reproduce the above copyright
133 ** notice, this list of conditions and the following disclaimer in
134 ** the documentation and/or other materials provided with the
135 ** distribution.
136 **
137 ** 3 Neither the name of the Standards Of Fundamental Astronomy Board,
138 ** the International Astronomical Union nor the names of its
139 ** contributors may be used to endorse or promote products derived
140 ** from this software without specific prior written permission.
141 **
142 ** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
143 ** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
144 ** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
145 ** FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
146 ** COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
147 ** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
148 ** BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
149 ** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
150 ** CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
151 ** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
152 ** ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
153 ** POSSIBILITY OF SUCH DAMAGE.
154 **
155 */
ERFA_WGS84
#define ERFA_WGS84
Definition: erfam.h:140
ERFA_GRS80
#define ERFA_GRS80
Definition: erfam.h:141
ERFA_WGS72
#define ERFA_WGS72
Definition: erfam.h:142
eraEform
int eraEform(int n, double *a, double *f)
Definition: eform.c:3