source: trunk/FACT++/pal/palDeuler.c

Last change on this file was 18347, checked in by tbretz, 9 years ago
File size: 3.9 KB
Line 
1/*
2*+
3* Name:
4* palDeuler
5
6* Purpose:
7* Form a rotation matrix from the Euler angles
8
9* Language:
10* Starlink ANSI C
11
12* Type of Module:
13* Library routine
14
15* Invocation:
16* void palDeuler ( const char *order, double phi, double theta, double psi,
17* double rmat[3][3] );
18
19* Arguments:
20* order = const char[] (Given)
21* Specifies about which axes the rotation occurs
22* phi = double (Given)
23* 1st rotation (radians)
24* theta = double (Given)
25* 2nd rotation (radians)
26* psi = double (Given)
27* 3rd rotation (radians)
28* rmat = double[3][3] (Given & Returned)
29* Rotation matrix
30
31* Description:
32* A rotation is positive when the reference frame rotates
33* anticlockwise as seen looking towards the origin from the
34* positive region of the specified axis.
35*
36* The characters of ORDER define which axes the three successive
37* rotations are about. A typical value is 'ZXZ', indicating that
38* RMAT is to become the direction cosine matrix corresponding to
39* rotations of the reference frame through PHI radians about the
40* old Z-axis, followed by THETA radians about the resulting X-axis,
41* then PSI radians about the resulting Z-axis.
42*
43* The axis names can be any of the following, in any order or
44* combination: X, Y, Z, uppercase or lowercase, 1, 2, 3. Normal
45* axis labelling/numbering conventions apply; the xyz (=123)
46* triad is right-handed. Thus, the 'ZXZ' example given above
47* could be written 'zxz' or '313' (or even 'ZxZ' or '3xZ'). ORDER
48* is terminated by length or by the first unrecognized character.
49*
50* Fewer than three rotations are acceptable, in which case the later
51* angle arguments are ignored. If all rotations are zero, the
52* identity matrix is produced.
53
54* Authors:
55* PTW: Pat Wallace (STFC)
56* TIMJ: Tim Jenness (JAC, Hawaii)
57* {enter_new_authors_here}
58
59* History:
60* 2012-02-08 (TIMJ):
61* Initial version with documentation taken from Fortran SLA
62* Adapted with permission from the Fortran SLALIB library.
63* {enter_further_changes_here}
64
65* Copyright:
66* Copyright (C) 1997 Rutherford Appleton Laboratory
67* Copyright (C) 2012 Science and Technology Facilities Council.
68* All Rights Reserved.
69
70* Licence:
71* This program is free software: you can redistribute it and/or
72* modify it under the terms of the GNU Lesser General Public
73* License as published by the Free Software Foundation, either
74* version 3 of the License, or (at your option) any later
75* version.
76*
77* This program is distributed in the hope that it will be useful,
78* but WITHOUT ANY WARRANTY; without even the implied warranty of
79* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
80* GNU Lesser General Public License for more details.
81*
82* You should have received a copy of the GNU Lesser General
83* License along with this program. If not, see
84* <http://www.gnu.org/licenses/>.
85
86* Bugs:
87* {note_any_bugs_here}
88*-
89*/
90
91#include "pal.h"
92#include "pal1sofa.h"
93
94void
95palDeuler( const char *order, double phi, double theta, double psi,
96 double rmat[3][3] ) {
97 int i = 0;
98 double rotations[3];
99
100 /* Initialise rmat */
101 eraIr( rmat );
102
103 /* copy the rotations into an array */
104 rotations[0] = phi;
105 rotations[1] = theta;
106 rotations[2] = psi;
107
108 /* maximum three rotations */
109 while (i < 3 && order[i] != '\0') {
110
111 switch (order[i]) {
112 case 'X':
113 case 'x':
114 case '1':
115 eraRx( rotations[i], rmat );
116 break;
117
118 case 'Y':
119 case 'y':
120 case '2':
121 eraRy( rotations[i], rmat );
122 break;
123
124 case 'Z':
125 case 'z':
126 case '3':
127 eraRz( rotations[i], rmat );
128 break;
129
130 default:
131 /* break out the loop if we do not recognize something */
132 i = 3;
133
134 }
135
136 /* Go to the next position */
137 i++;
138 }
139
140 return;
141}
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