SUBROUTINE iau_EFORM ( N, A, F, J ) *+ * - - - - - - - - - - * i a u _ E F O R M * - - - - - - - - - - * * Earth reference ellipsoids. * * This routine is part of the International Astronomical Union's * SOFA (Standards of Fundamental Astronomy) software collection. * * Status: canonical. * * Given: * N i ellipsoid identifier (Note 1) * * Returned: * A d equatorial radius (meters, Note 2) * F d flattening (Note 2) * J i status: 0 = OK * -1 = illegal identifier (Note 3) * * Notes: * * 1) The identifier N is a number that specifies the choice of * reference ellipsoid. The following are supported: * * N ellipsoid * * 1 WGS84 * 2 GRS80 * 3 WGS72 * * The number N has no significance outside the SOFA software. * * 2) The ellipsoid parameters are returned in the form of equatorial * radius in meters (A) and flattening (F). The latter is a number * around 0.00335, i.e. around 1/298. * * 3) For the case where an unsupported N value is supplied, zero A and * F are returned, as well as error status. * * References: * * Department of Defense World Geodetic System 1984, National Imagery * and Mapping Agency Technical Report 8350.2, Third Edition, p3-2. * * Moritz, H., Bull. Geodesique 66-2, 187 (1992). * * The Department of Defense World Geodetic System 1972, World * Geodetic System Committee, May 1974. * * Explanatory Supplement to the Astronomical Almanac, * P. Kenneth Seidelmann (ed), University Science Books (1992), * p220. * * This revision: 2010 January 18 * * SOFA release 2021-05-12 * * Copyright (C) 2021 IAU SOFA Board. See notes at end. * *----------------------------------------------------------------------- IMPLICIT NONE INTEGER N DOUBLE PRECISION A, F INTEGER J * - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - * Preset the status to OK J = 0 * Look up A and F for the specified reference ellipsoid. IF ( N.EQ.1 ) THEN * WGS84. A = 6378137D0 F = 1D0 / 298.257223563D0 ELSE IF ( N.EQ.2 ) THEN * GRS80. A = 6378137D0 F = 1D0 / 298.257222101D0 ELSE IF ( N.EQ.3 ) THEN * WGS72. A = 6378135D0 F = 1D0 / 298.26D0 ELSE * Invalid identifier. A = 0D0 F = 0D0 J = -1 END IF * 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. 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. That portion of your * distribution that does not consist of intact and unchanged copies * of SOFA source code files is a "derived work" that must comply * with the following requirements: * * a) Your work shall be marked or carry a statement that it * (i) uses routines and computations derived by you from * software provided by SOFA under license to you; and * (ii) does not itself constitute software provided by and/or * endorsed by SOFA. * * b) The source code of your derived work must contain descriptions * of how the derived work is based upon, contains and/or differs * from the original SOFA software. * * c) The names of all routines in your derived work shall not * include the prefix "iau" or "sofa" or trivial modifications * thereof such as changes of case. * * d) The origin of the SOFA components of your derived work must * not be misrepresented; you must not claim that you wrote the * original software, nor file a patent application for SOFA * software or algorithms embedded in the SOFA software. * * e) These requirements must be reproduced intact in any source * distribution and shall apply to anyone to whom you have * granted a further right to modify the source code of your * derived work. * * Note that, as originally distributed, the SOFA software is * intended to be a definitive implementation of the IAU standards, * and consequently third-party modifications are discouraged. All * variations, no matter how minor, must be explicitly marked as * such, as explained above. * * 4. You shall not cause the SOFA software to be brought into * disrepute, either by misuse, or use for inappropriate tasks, or * by inappropriate modification. * * 5. The SOFA software is provided "as is" and SOFA makes no warranty * as to its use or performance. SOFA does not and cannot warrant * the performance or results which the user may obtain by using the * SOFA software. SOFA makes no warranties, express or implied, as * to non-infringement of third party rights, merchantability, or * fitness for any particular purpose. In no event will SOFA be * liable to the user for any consequential, incidental, or special * damages, including any lost profits or lost savings, even if a * SOFA representative has been advised of such damages, or for any * claim by any third party. * * 6. 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