SUBROUTINE iau_FW2M ( GAMB, PHIB, PSI, EPS, R ) *+ * - - - - - - - - - * i a u _ F W 2 M * - - - - - - - - - * * Form rotation matrix given the Fukushima-Williams angles. * * This routine is part of the International Astronomical Union's * SOFA (Standards of Fundamental Astronomy) software collection. * * Status: support routine. * * Given: * GAMB d F-W angle gamma_bar (radians) * PHIB d F-W angle phi_bar (radians) * PSI d F-W angle psi (radians) * EPS d F-W angle epsilon (radians) * * Returned: * R d(3,3) rotation matrix * * Notes: * * 1) Naming the following points: * * e = J2000.0 ecliptic pole, * p = GCRS pole, * E = ecliptic pole of date, * and P = CIP, * * the four Fukushima-Williams angles are as follows: * * GAMB = gamma = epE * PHIB = phi = pE * PSI = psi = pEP * EPS = epsilon = EP * * 2) The matrix representing the combined effects of frame bias, * precession and nutation is: * * NxPxB = R_1(-EPS).R_3(-PSI).R_1(PHIB).R_3(GAMB) * * 3) The present routine can construct three different matrices, * depending on which angles are supplied as the arguments GAMB, * PHIB, PSI and EPS: * * o To obtain the nutation x precession x frame bias matrix, * first generate the four precession angles known conventionally * as gamma_bar, phi_bar, psi_bar and epsilon_A, then generate * the nutation components Dpsi and Depsilon and add them to * psi_bar and epsilon_A, and finally call the present routine * using those four angles as arguments. * * o To obtain the precession x frame bias matrix, generate the * four precession angles and call the present routine. * * o To obtain the frame bias matrix, generate the four precession * angles for date J2000.0 and call the present routine. * * The nutation-only and precession-only matrices can if necessary * be obtained by combining these three appropriately. * * Called: * iau_IR initialize r-matrix to identity * iau_RZ rotate around Z-axis * iau_RX rotate around X-axis * * References: * * Capitaine, N. & Wallace, P.T., 2006, Astron.Astrophys. 450, 855 * * Hilton, J. et al., 2006, Celest.Mech.Dyn.Astron. 94, 351 * * This revision: 2020 November 17 * * SOFA release 2021-05-12 * * Copyright (C) 2021 IAU SOFA Board. See notes at end. * *----------------------------------------------------------------------- IMPLICIT NONE DOUBLE PRECISION GAMB, PHIB, PSI, EPS, R(3,3) * - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - * Construct the matrix. CALL iau_IR ( R ) CALL iau_RZ ( GAMB, R ) CALL iau_RX ( PHIB, R ) CALL iau_RZ ( -PSI, R ) CALL iau_RX ( -EPS, R ) * Finished. *+---------------------------------------------------------------------- * * Copyright (C) 2021 * 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. 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