source: trunk/FACT++/erfa/src/gd2gce.c@ 19594

Last change on this file since 19594 was 18921, checked in by tbretz, 8 years ago
Updated to ERFA 1.4.0
File size: 5.4 KB
Line 
1#include "erfa.h"
2
3int eraGd2gce ( double a, double f, double elong, double phi,
4 double height, double xyz[3] )
5/*
6** - - - - - - - - - -
7** e r a G d 2 g c e
8** - - - - - - - - - -
9**
10** Transform geodetic coordinates to geocentric for a reference
11** ellipsoid of specified form.
12**
13** Given:
14** a double equatorial radius (Notes 1,4)
15** f double flattening (Notes 2,4)
16** elong double longitude (radians, east +ve)
17** phi double latitude (geodetic, radians, Note 4)
18** height double height above ellipsoid (geodetic, Notes 3,4)
19**
20** Returned:
21** xyz double[3] geocentric vector (Note 3)
22**
23** Returned (function value):
24** int status: 0 = OK
25** -1 = illegal case (Note 4)
26** Notes:
27**
28** 1) The equatorial radius, a, can be in any units, but meters is
29** the conventional choice.
30**
31** 2) The flattening, f, is (for the Earth) a value around 0.00335,
32** i.e. around 1/298.
33**
34** 3) The equatorial radius, a, and the height, height, must be
35** given in the same units, and determine the units of the
36** returned geocentric vector, xyz.
37**
38** 4) No validation is performed on individual arguments. The error
39** status -1 protects against (unrealistic) cases that would lead
40** to arithmetic exceptions. If an error occurs, xyz is unchanged.
41**
42** 5) The inverse transformation is performed in the function
43** eraGc2gde.
44**
45** 6) The transformation for a standard ellipsoid (such as ERFA_WGS84) can
46** more conveniently be performed by calling eraGd2gc, which uses a
47** numerical code to identify the required a and f values.
48**
49** References:
50**
51** Green, R.M., Spherical Astronomy, Cambridge University Press,
52** (1985) Section 4.5, p96.
53**
54** Explanatory Supplement to the Astronomical Almanac,
55** P. Kenneth Seidelmann (ed), University Science Books (1992),
56** Section 4.22, p202.
57**
58** Copyright (C) 2013-2017, NumFOCUS Foundation.
59** Derived, with permission, from the SOFA library. See notes at end of file.
60*/
61{
62 double sp, cp, w, d, ac, as, r;
63
64
65/* Functions of geodetic latitude. */
66 sp = sin(phi);
67 cp = cos(phi);
68 w = 1.0 - f;
69 w = w * w;
70 d = cp*cp + w*sp*sp;
71 if ( d <= 0.0 ) return -1;
72 ac = a / sqrt(d);
73 as = w * ac;
74
75/* Geocentric vector. */
76 r = (ac + height) * cp;
77 xyz[0] = r * cos(elong);
78 xyz[1] = r * sin(elong);
79 xyz[2] = (as + height) * sp;
80
81/* Success. */
82 return 0;
83
84}
85/*----------------------------------------------------------------------
86**
87**
88** Copyright (C) 2013-2017, NumFOCUS Foundation.
89** All rights reserved.
90**
91** This library is derived, with permission, from the International
92** Astronomical Union's "Standards of Fundamental Astronomy" library,
93** available from http://www.iausofa.org.
94**
95** The ERFA version is intended to retain identical functionality to
96** the SOFA library, but made distinct through different function and
97** file names, as set out in the SOFA license conditions. The SOFA
98** original has a role as a reference standard for the IAU and IERS,
99** and consequently redistribution is permitted only in its unaltered
100** state. The ERFA version is not subject to this restriction and
101** therefore can be included in distributions which do not support the
102** concept of "read only" software.
103**
104** Although the intent is to replicate the SOFA API (other than
105** replacement of prefix names) and results (with the exception of
106** bugs; any that are discovered will be fixed), SOFA is not
107** responsible for any errors found in this version of the library.
108**
109** If you wish to acknowledge the SOFA heritage, please acknowledge
110** that you are using a library derived from SOFA, rather than SOFA
111** itself.
112**
113**
114** TERMS AND CONDITIONS
115**
116** Redistribution and use in source and binary forms, with or without
117** modification, are permitted provided that the following conditions
118** are met:
119**
120** 1 Redistributions of source code must retain the above copyright
121** notice, this list of conditions and the following disclaimer.
122**
123** 2 Redistributions in binary form must reproduce the above copyright
124** notice, this list of conditions and the following disclaimer in
125** the documentation and/or other materials provided with the
126** distribution.
127**
128** 3 Neither the name of the Standards Of Fundamental Astronomy Board,
129** the International Astronomical Union nor the names of its
130** contributors may be used to endorse or promote products derived
131** from this software without specific prior written permission.
132**
133** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
134** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
135** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
136** FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
137** COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
138** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
139** BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
140** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
141** CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
142** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
143** ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
144** POSSIBILITY OF SUCH DAMAGE.
145**
146*/
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