source: branches/FACT++_lidctrl_usb/erfa/src/gd2gce.c@ 19875

Last change on this file since 19875 was 18711, checked in by tbretz, 10 years ago
Updated to ERFA 1.3.0 (no relevant code change except the leap second at the beginning of 2017)
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) 2013-2016, 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) 2013-2016, 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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