SUBROUTINE iau_FW2XY ( GAMB, PHIB, PSI, EPS, X, Y ) *+ * - - - - - - - - - - * i a u _ F W 2 X Y * - - - - - - - - - - * * CIP X,Y given Fukushima-Williams bias-precession-nutation 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: * X,Y d CIP unit vector X,Y * * 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(-EPSA).R_3(-PSI).R_1(PHIB).R_3(GAMB) * * The returned values x,y are elements (3,1) and (3,2) of the * matrix. Near J2000.0, they are essentially angles in radians. * * Called: * iau_FW2M F-W angles to r-matrix * iau_BPN2XY extract CIP X,Y coordinates from NPB matrix * * Reference: * * Hilton, J. et al., 2006, Celest.Mech.Dyn.Astron. 94, 351 * * This revision: 2013 September 2 * * SOFA release 2023-10-11 * * Copyright (C) 2023 IAU SOFA Board. See notes at end. * *----------------------------------------------------------------------- IMPLICIT NONE DOUBLE PRECISION GAMB, PHIB, PSI, EPS, X, Y DOUBLE PRECISION R(3,3) * - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - * Form NxPxB matrix. CALL iau_FW2M ( GAMB, PHIB, PSI, EPS, R ) * Extract CIP X,Y. CALL iau_BPN2XY ( R, X, Y ) * Finished. *+---------------------------------------------------------------------- * * Copyright (C) 2023 * 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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