## File: palDeuler.c

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 `123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141` ``````/* *+ * Name: * palDeuler * Purpose: * Form a rotation matrix from the Euler angles * Language: * Starlink ANSI C * Type of Module: * Library routine * Invocation: * void palDeuler ( const char *order, double phi, double theta, double psi, * double rmat[3][3] ); * Arguments: * order = const char[] (Given) * Specifies about which axes the rotation occurs * phi = double (Given) * 1st rotation (radians) * theta = double (Given) * 2nd rotation (radians) * psi = double (Given) * 3rd rotation (radians) * rmat = double[3][3] (Given & Returned) * Rotation matrix * Description: * A rotation is positive when the reference frame rotates * anticlockwise as seen looking towards the origin from the * positive region of the specified axis. * * The characters of ORDER define which axes the three successive * rotations are about. A typical value is 'ZXZ', indicating that * RMAT is to become the direction cosine matrix corresponding to * rotations of the reference frame through PHI radians about the * old Z-axis, followed by THETA radians about the resulting X-axis, * then PSI radians about the resulting Z-axis. * * The axis names can be any of the following, in any order or * combination: X, Y, Z, uppercase or lowercase, 1, 2, 3. Normal * axis labelling/numbering conventions apply; the xyz (=123) * triad is right-handed. Thus, the 'ZXZ' example given above * could be written 'zxz' or '313' (or even 'ZxZ' or '3xZ'). ORDER * is terminated by length or by the first unrecognized character. * * Fewer than three rotations are acceptable, in which case the later * angle arguments are ignored. If all rotations are zero, the * identity matrix is produced. * Authors: * PTW: Pat Wallace (STFC) * TIMJ: Tim Jenness (JAC, Hawaii) * {enter_new_authors_here} * History: * 2012-02-08 (TIMJ): * Initial version with documentation taken from Fortran SLA * Adapted with permission from the Fortran SLALIB library. * {enter_further_changes_here} * Copyright: * Copyright (C) 1997 Rutherford Appleton Laboratory * Copyright (C) 2012 Science and Technology Facilities Council. * All Rights Reserved. * Licence: * This program is free software: you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation, either * version 3 of the License, or (at your option) any later * version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General * License along with this program. If not, see * . * Bugs: * {note_any_bugs_here} *- */ #include "pal.h" #include "pal1sofa.h" void palDeuler( const char *order, double phi, double theta, double psi, double rmat[3][3] ) { int i = 0; double rotations[3]; /* Initialise rmat */ eraIr( rmat ); /* copy the rotations into an array */ rotations[0] = phi; rotations[1] = theta; rotations[2] = psi; /* maximum three rotations */ while (i < 3 && order[i] != '\0') { switch (order[i]) { case 'X': case 'x': case '1': eraRx( rotations[i], rmat ); break; case 'Y': case 'y': case '2': eraRy( rotations[i], rmat ); break; case 'Z': case 'z': case '3': eraRz( rotations[i], rmat ); break; default: /* break out the loop if we do not recognize something */ i = 3; } /* Go to the next position */ i++; } return; } ``````