SUBROUTINE iau_CAL2JD ( IY, IM, ID, DJM0, DJM, J ) *+ * - - - - - - - - - - - * i a u _ C A L 2 J D * - - - - - - - - - - - * * Gregorian Calendar to Julian Date. * * This routine is part of the International Astronomical Union's * SOFA (Standards of Fundamental Astronomy) software collection. * * Status: support routine. * * Given: * IY,IM,ID i year, month, day in Gregorian calendar (Note 1) * * Returned: * DJM0 d MJD zero-point: always 2400000.5D0 * DJM d Modified Julian Date for 0 hrs * J i status: * 0 = OK * -1 = bad year (Note 3: JD not computed) * -2 = bad month (JD not computed) * -3 = bad day (JD computed) * * Notes: * * 1) The algorithm used is valid from -4800 March 1, but this * implementation rejects dates before -4799 January 1. * * 2) The Julian Date is returned in two pieces, in the usual SOFA * manner, which is designed to preserve time resolution. The * Julian Date is available as a single number by adding DJM0 and * DJM. * * 3) In early eras the conversion is from the "Proleptic Gregorian * Calendar"; no account is taken of the date(s) of adoption of * the Gregorian Calendar, nor is the AD/BC numbering convention * observed. * * Reference: * * Explanatory Supplement to the Astronomical Almanac, * P. Kenneth Seidelmann (ed), University Science Books (1992), * Section 12.92 (p604). * * This revision: 2020 October 21 * * SOFA release 2023-10-11 * * Copyright (C) 2023 IAU SOFA Board. See notes at end. * *----------------------------------------------------------------------- IMPLICIT NONE INTEGER IY, IM, ID DOUBLE PRECISION DJM0, DJM INTEGER J, NDAYS, MY, IYPMY * Earliest year allowed (4800BC) INTEGER IYMIN PARAMETER ( IYMIN = -4799 ) * Month lengths in days INTEGER MTAB(12) DATA MTAB / 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 / * - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - * Preset status. J = 0 * Validate year. IF ( IY.LT.IYMIN ) THEN J = -1 ELSE * Validate month. IF ( IM.GE.1 .AND. IM.LE.12 ) THEN * Days in current month. NDAYS = MTAB(IM) * Allow for leap year. IF ( IM .EQ. 2 ) THEN IF ( MOD(IY,4) .EQ. 0 ) NDAYS = 29 IF ( MOD(IY,100).EQ.0 .AND. : MOD(IY,400).NE.0 ) NDAYS = 28 END IF * Validate day. IF ( ID.LT.1 .OR. ID.GT.NDAYS ) J = -3 * Result. MY = ( IM - 14 ) / 12 IYPMY = IY + MY DJM0 = 2400000.5D0 DJM = DBLE( ( 1461 * ( IYPMY + 4800 ) ) / 4 : + ( 367 * ( IM-2 - 12*MY ) ) / 12 : - ( 3 * ( ( IYPMY + 4900 ) / 100 ) ) / 4 : + ID - 2432076) * Bad month ELSE J = -2 END IF END IF * 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. 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