SUBROUTINE iau_D2DTF ( SCALE, NDP, D1, D2, IY, IM, ID, IHMSF, J ) *+ * - - - - - - - - - - * i a u _ D 2 D T F * - - - - - - - - - - * * Format for output a 2-part Julian Date (or in the case of UTC a * quasi-JD form that includes special provision for leap seconds). * * This routine is part of the International Astronomical Union's * SOFA (Standards of Fundamental Astronomy) software collection. * * Status: support routine. * * Given: * SCALE c*(*) time scale ID (Note 1) * NDP i resolution (Note 2) * D1,D2 d time as a 2-part Julian Date (Notes 3,4) * * Returned: * IY,IM,ID i year, month, day in Gregorian calendar (Note 5) * IHMSF i(4) hours, minutes, seconds, fraction (Note 1) * J i status: +1 = dubious year (Note 5) * 0 = OK * -1 = unacceptable date (Note 6) * * Notes: * * 1) SCALE identifies the time scale. Only the value 'UTC' (in upper * case) is significant, and enables handling of leap seconds (see * Note 4). * * 2) NDP is the number of decimal places in the seconds field, and can * have negative as well as positive values, such as: * * NDP resolution * -4 1 00 00 * -3 0 10 00 * -2 0 01 00 * -1 0 00 10 * 0 0 00 01 * 1 0 00 00.1 * 2 0 00 00.01 * 3 0 00 00.001 * * The limits are platform dependent, but a safe range is -5 to +9. * * 3) D1+D2 is Julian Date, apportioned in any convenient way between * the two arguments, for example where D1 is the Julian Day Number * and D2 is the fraction of a day. In the case of UTC, where the * use of JD is problematical, special conventions apply: see the * next note. * * 4) JD cannot unambiguously represent UTC during a leap second unless * special measures are taken. The SOFA internal convention is that * the quasi-JD day represents UTC days whether the length is 86399, * 86400 or 86401 SI seconds. In the 1960-1972 era there were * smaller jumps (in either direction) each time the linear UTC(TAI) * expression was changed, and these "mini-leaps" are also included * in the SOFA convention. * * 5) The warning status "dubious year" flags UTCs that predate the * introduction of the time scale or that are too far in the future * to be trusted. See iau_DAT for further details. * * 6) For calendar conventions and limitations, see iau_CAL2JD. * * Called: * iau_JD2CAL JD to Gregorian calendar * iau_D2TF decompose days to hms * iau_DAT delta(AT) = TAI-UTC * * This revision: 2021 February 12 * * SOFA release 2021-01-25 * * Copyright (C) 2021 IAU SOFA Board. See notes at end. * *----------------------------------------------------------------------- IMPLICIT NONE CHARACTER*(*) SCALE INTEGER NDP DOUBLE PRECISION D1, D2 INTEGER IY, IM, ID, IHMSF(4), J * Days to seconds DOUBLE PRECISION D2S PARAMETER ( D2S = 86400D0 ) LOGICAL LEAP CHARACTER S INTEGER IY1, IM1, ID1, JS, IY2, IM2, ID2, IHMSF1(4), I DOUBLE PRECISION A1, B1, FD, DAT0, DAT12, W, DAT24, DLEAP * - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - * The two-part JD. A1 = D1 B1 = D2 * Provisional calendar date. CALL iau_JD2CAL ( A1, B1, IY1, IM1, ID1, FD, JS ) IF ( JS.NE.0 ) GO TO 9 * Is this a leap second day? LEAP = .FALSE. IF ( SCALE.EQ.'UTC' ) THEN * TAI-UTC at 0h today. CALL iau_DAT ( IY1, IM1, ID1, 0D0, DAT0, JS ) IF ( JS.LT.0 ) GO TO 9 * TAI-UTC at 12h today (to detect drift). CALL iau_DAT ( IY1, IM1, ID1, 0.5D0, DAT12, JS ) IF ( JS.LT.0 ) GO TO 9 * TAI-UTC at 0h tomorrow (to detect jumps). CALL iau_JD2CAL ( A1+1.5D0, B1-FD, IY2, IM2, ID2, W, JS ) IF ( JS.NE.0 ) GO TO 9 CALL iau_DAT ( IY2, IM2, ID2, 0D0, DAT24, JS ) IF ( JS.LT.0 ) GO TO 9 * Any sudden change in TAI-UTC (seconds). DLEAP = DAT24 - ( 2D0 * DAT12 - DAT0 ) * If leap second day, scale the fraction of a day into SI. LEAP = ABS(DLEAP) .GT. 0.5D0 IF ( LEAP ) FD = FD + FD*DLEAP/D2S END IF * Provisional time of day. CALL iau_D2TF ( NDP, FD, S, IHMSF1 ) * Has the (rounded) time gone past 24h? IF ( IHMSF1(1).GT.23 ) THEN * Yes. We probably need tomorrow's calendar date. CALL iau_JD2CAL ( A1+1.5D0, B1-FD, IY2, IM2, ID2, W, JS ) IF ( JS.LT.0 ) GO TO 9 * Is today a leap second day? IF ( .NOT. LEAP ) THEN * No. Use 0h tomorrow. IY1 = IY2 IM1 = IM2 ID1 = ID2 IHMSF1(1) = 0 IHMSF1(2) = 0 IHMSF1(3) = 0 ELSE * Yes. Are we past the leap second itself? IF ( IHMSF1(3).GT.0 ) THEN * Yes. Use tomorrow but allow for the leap second. IY1 = IY2 IM1 = IM2 ID1 = ID2 IHMSF1(1) = 0 IHMSF1(2) = 0 IHMSF1(3) = 0 ELSE * No. Use 23 59 60... today. IHMSF1(1) = 23 IHMSF1(2) = 59 IHMSF1(3) = 60 END IF * If rounding to 10s or coarser always go up to new day. IF ( NDP.LT.0 .AND. IHMSF1(3).EQ.60 ) THEN IY1 = IY2 IM1 = IM2 ID1 = ID2 IHMSF1(1) = 0 IHMSF1(2) = 0 IHMSF1(3) = 0 END IF END IF END IF * Results. IY = IY1 IM = IM1 ID = ID1 DO 2 I=1,4 IHMSF(I) = IHMSF1(I) 2 CONTINUE * Status. 9 CONTINUE J = JS * 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. 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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