File Coverage

erfasrc/src/hd2pa.c

Criterion	Covered	Total	%
statement	0	5	0.0
branch	0	2	0.0
condition			n/a
subroutine			n/a
pod			n/a
total	0	7	0.0

line	stmt	bran	code
1			#include "erfa.h"
2
3	0		double eraHd2pa (double ha, double dec, double phi)
4			/*
5			** - - - - - - - - -
6			** e r a H d 2 p a
7			** - - - - - - - - -
8			**
9			** Parallactic angle for a given hour angle and declination.
10			**
11			** Given:
12			** ha double hour angle
13			** dec double declination
14			** phi double site latitude
15			**
16			** Returned (function value):
17			** double parallactic angle
18			**
19			** Notes:
20			**
21			** 1) All the arguments are angles in radians.
22			**
23			** 2) The parallactic angle at a point in the sky is the position
24			** angle of the vertical, i.e. the angle between the directions to
25			** the north celestial pole and to the zenith respectively.
26			**
27			** 3) The result is returned in the range -pi to +pi.
28			**
29			** 4) At the pole itself a zero result is returned.
30			**
31			** 5) The latitude phi is pi/2 minus the angle between the Earth's
32			** rotation axis and the adopted zenith. In many applications it
33			** will be sufficient to use the published geodetic latitude of the
34			** site. In very precise (sub-arcsecond) applications, phi can be
35			** corrected for polar motion.
36			**
37			** 6) Should the user wish to work with respect to the astronomical
38			** zenith rather than the geodetic zenith, phi will need to be
39			** adjusted for deflection of the vertical (often tens of
40			** arcseconds), and the zero point of the hour angle ha will also
41			** be affected.
42			**
43			** Reference:
44			** Smart, W.M., "Spherical Astronomy", Cambridge University Press,
45			** 6th edition (Green, 1977), p49.
46			**
47			** Last revision: 2017 September 12
48			**
49			** ERFA release 2020-07-21
50			**
51			** Copyright (C) 2020 IAU ERFA Board. See notes at end.
52			*/
53			{
54			double cp, cqsz, sqsz;
55
56
57	0		cp = cos(phi);
58	0		sqsz = cp*sin(ha);
59	0		cqsz = sin(phi)cos(dec) - cpsin(dec)*cos(ha);
60	0	0	return ( ( sqsz != 0.0 \|\| cqsz != 0.0 ) ? atan2(sqsz,cqsz) : 0.0 );
61
62			/* Finished. */
63
64			}
65			/*----------------------------------------------------------------------
66			**
67			**
68			** Copyright (C) 2013-2020, NumFOCUS Foundation.
69			** All rights reserved.
70			**
71			** This library is derived, with permission, from the International
72			** Astronomical Union's "Standards of Fundamental Astronomy" library,
73			** available from http://www.iausofa.org.
74			**
75			** The ERFA version is intended to retain identical functionality to
76			** the SOFA library, but made distinct through different function and
77			** file names, as set out in the SOFA license conditions. The SOFA
78			** original has a role as a reference standard for the IAU and IERS,
79			** and consequently redistribution is permitted only in its unaltered
80			** state. The ERFA version is not subject to this restriction and
81			** therefore can be included in distributions which do not support the
82			** concept of "read only" software.
83			**
84			** Although the intent is to replicate the SOFA API (other than
85			** replacement of prefix names) and results (with the exception of
86			** bugs; any that are discovered will be fixed), SOFA is not
87			** responsible for any errors found in this version of the library.
88			**
89			** If you wish to acknowledge the SOFA heritage, please acknowledge
90			** that you are using a library derived from SOFA, rather than SOFA
91			** itself.
92			**
93			**
94			** TERMS AND CONDITIONS
95			**
96			** Redistribution and use in source and binary forms, with or without
97			** modification, are permitted provided that the following conditions
98			** are met:
99			**
100			** 1 Redistributions of source code must retain the above copyright
101			** notice, this list of conditions and the following disclaimer.
102			**
103			** 2 Redistributions in binary form must reproduce the above copyright
104			** notice, this list of conditions and the following disclaimer in
105			** the documentation and/or other materials provided with the
106			** distribution.
107			**
108			** 3 Neither the name of the Standards Of Fundamental Astronomy Board,
109			** the International Astronomical Union nor the names of its
110			** contributors may be used to endorse or promote products derived
111			** from this software without specific prior written permission.
112			**
113			** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
114			** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
115			** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
116			** FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
117			** COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
118			** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
119			** BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
120			** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
121			** CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
122			** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
123			** ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
124			** POSSIBILITY OF SUCH DAMAGE.
125			**
126			*/