SUBROUTINE iau_RX ( PHI, R ) *+ * - - - - - - - * i a u _ R X * - - - - - - - * * Rotate an r-matrix about the x-axis. * * This routine is part of the International Astronomical Union's * SOFA (Standards of Fundamental Astronomy) software collection. * * Status: vector/matrix support routine. * * Given: * PHI d angle (radians) * * Given and returned: * R d(3,3) r-matrix, rotated * * Notes: * * 1) Calling this routine with positive PHI incorporates in the * supplied r-matrix R an additional rotation, about the x-axis, * anticlockwise as seen looking towards the origin from positive x. * * 2) The additional rotation can be represented by this matrix: * * ( 1 0 0 ) * ( ) * ( 0 + cos(PHI) + sin(PHI) ) * ( ) * ( 0 - sin(PHI) + cos(PHI) ) * * This revision: 2012 April 3 * * SOFA release 2020-07-21 * * Copyright (C) 2020 IAU SOFA Board. See notes at end. * *----------------------------------------------------------------------- IMPLICIT NONE DOUBLE PRECISION PHI, R(3,3) DOUBLE PRECISION S, C, A21, A22, A23, A31, A32, A33 * - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - S = SIN(PHI) C = COS(PHI) A21 = C*R(2,1) + S*R(3,1) A22 = C*R(2,2) + S*R(3,2) A23 = C*R(2,3) + S*R(3,3) A31 = - S*R(2,1) + C*R(3,1) A32 = - S*R(2,2) + C*R(3,2) A33 = - S*R(2,3) + C*R(3,3) R(2,1) = A21 R(2,2) = A22 R(2,3) = A23 R(3,1) = A31 R(3,2) = A32 R(3,3) = A33 * Finished. *+---------------------------------------------------------------------- * * Copyright (C) 2020 * Standards Of Fundamental Astronomy Board * of the International Astronomical Union. * * ===================== * SOFA Software License * ===================== * * NOTICE TO USER: * * BY USING THIS SOFTWARE YOU ACCEPT THE FOLLOWING SIX TERMS AND * CONDITIONS WHICH APPLY TO ITS USE. * * 1. The Software is owned by the IAU SOFA Board ("SOFA"). * * 2. Permission is granted to anyone to use the SOFA software for any * purpose, including commercial applications, free of charge and * without payment of royalties, subject to the conditions and * restrictions listed below. * * 3. You (the user) may copy and distribute SOFA source code to others, * and use and adapt its code and algorithms in your own software, * on a world-wide, royalty-free basis. 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The provision of any version of the SOFA software under the terms * and conditions specified herein does not imply that future * versions will also be made available under the same terms and * conditions. * * In any published work or commercial product which uses the SOFA * software directly, acknowledgement (see www.iausofa.org) is * appreciated. * * Correspondence concerning SOFA software should be addressed as * follows: * * By email: sofa@ukho.gov.uk * By post: IAU SOFA Center * HM Nautical Almanac Office * UK Hydrographic Office * Admiralty Way, Taunton * Somerset, TA1 2DN * United Kingdom * *----------------------------------------------------------------------- END