File Coverage

erfasrc/src/tpsts.c

Criterion	Covered	Total	%
statement	0	7	0.0
branch			n/a
condition			n/a
subroutine			n/a
pod			n/a
total	0	7	0.0

line	stmt	code
1		#include "erfa.h"
2
3	0	void eraTpsts(double xi, double eta, double a0, double b0,
4		double a, double b)
5		/*
6		** - - - - - - - - -
7		** e r a T p s t s
8		** - - - - - - - - -
9		**
10		** In the tangent plane projection, given the star's rectangular
11		** coordinates and the spherical coordinates of the tangent point,
12		** solve for the spherical coordinates of the star.
13		**
14		** Given:
15		** xi,eta double rectangular coordinates of star image (Note 2)
16		** a0,b0 double tangent point's spherical coordinates
17		**
18		** Returned:
19		** a,b double star's spherical coordinates
20		**
21		** 1) The tangent plane projection is also called the "gnomonic
22		** projection" and the "central projection".
23		**
24		** 2) The eta axis points due north in the adopted coordinate system.
25		** If the spherical coordinates are observed (RA,Dec), the tangent
26		** plane coordinates (xi,eta) are conventionally called the
27		** "standard coordinates". If the spherical coordinates are with
28		** respect to a right-handed triad, (xi,eta) are also right-handed.
29		** The units of (xi,eta) are, effectively, radians at the tangent
30		** point.
31		**
32		** 3) All angular arguments are in radians.
33		**
34		** 4) This function is a member of the following set:
35		**
36		** spherical vector solve for
37		**
38		** eraTpxes eraTpxev xi,eta
39		** > eraTpsts < eraTpstv star
40		** eraTpors eraTporv origin
41		**
42		** Called:
43		** eraAnp normalize angle into range 0 to 2pi
44		**
45		** References:
46		**
47		** Calabretta M.R. & Greisen, E.W., 2002, "Representations of
48		** celestial coordinates in FITS", Astron.Astrophys. 395, 1077
49		**
50		** Green, R.M., "Spherical Astronomy", Cambridge University Press,
51		** 1987, Chapter 13.
52		**
53		** Copyright (C) 2013-2019, NumFOCUS Foundation.
54		** Derived, with permission, from the SOFA library. See notes at end of file.
55		*/
56		{
57		double sb0, cb0, d;
58
59	0	sb0 = sin(b0);
60	0	cb0 = cos(b0);
61	0	d = cb0 - eta*sb0;
62	0	*a = eraAnp(atan2(xi,d) + a0);
63	0	b = atan2(sb0+etacb0, sqrt(xixi+dd));
64
65		/* Finished. */
66
67	0	}
68		/*----------------------------------------------------------------------
69		**
70		**
71		** Copyright (C) 2013-2019, NumFOCUS Foundation.
72		** All rights reserved.
73		**
74		** This library is derived, with permission, from the International
75		** Astronomical Union's "Standards of Fundamental Astronomy" library,
76		** available from http://www.iausofa.org.
77		**
78		** The ERFA version is intended to retain identical functionality to
79		** the SOFA library, but made distinct through different function and
80		** file names, as set out in the SOFA license conditions. The SOFA
81		** original has a role as a reference standard for the IAU and IERS,
82		** and consequently redistribution is permitted only in its unaltered
83		** state. The ERFA version is not subject to this restriction and
84		** therefore can be included in distributions which do not support the
85		** concept of "read only" software.
86		**
87		** Although the intent is to replicate the SOFA API (other than
88		** replacement of prefix names) and results (with the exception of
89		** bugs; any that are discovered will be fixed), SOFA is not
90		** responsible for any errors found in this version of the library.
91		**
92		** If you wish to acknowledge the SOFA heritage, please acknowledge
93		** that you are using a library derived from SOFA, rather than SOFA
94		** itself.
95		**
96		**
97		** TERMS AND CONDITIONS
98		**
99		** Redistribution and use in source and binary forms, with or without
100		** modification, are permitted provided that the following conditions
101		** are met:
102		**
103		** 1 Redistributions of source code must retain the above copyright
104		** notice, this list of conditions and the following disclaimer.
105		**
106		** 2 Redistributions in binary form must reproduce the above copyright
107		** notice, this list of conditions and the following disclaimer in
108		** the documentation and/or other materials provided with the
109		** distribution.
110		**
111		** 3 Neither the name of the Standards Of Fundamental Astronomy Board,
112		** the International Astronomical Union nor the names of its
113		** contributors may be used to endorse or promote products derived
114		** from this software without specific prior written permission.
115		**
116		** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
117		** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
118		** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
119		** FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
120		** COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
121		** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
122		** BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
123		** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
124		** CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
125		** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
126		** ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
127		** POSSIBILITY OF SUCH DAMAGE.
128		**
129		*/