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Francois NGUYEN
253
20200721/c/src/dtf2d.c
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253
20200721/c/src/dtf2d.c
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#include "sofa.h"
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#include <string.h>
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int iauDtf2d(const char *scale, int iy, int im, int id,
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int ihr, int imn, double sec, double *d1, double *d2)
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/*
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** - - - - - - - - -
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** i a u D t f 2 d
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** - - - - - - - - -
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**
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** Encode date and time fields into 2-part Julian Date (or in the case
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** of UTC a quasi-JD form that includes special provision for leap
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** seconds).
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**
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** This function is part of the International Astronomical Union's
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** SOFA (Standards of Fundamental Astronomy) software collection.
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**
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** Status: support function.
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**
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** Given:
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** scale char[] time scale ID (Note 1)
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** iy,im,id int year, month, day in Gregorian calendar (Note 2)
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** ihr,imn int hour, minute
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** sec double seconds
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**
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** Returned:
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** d1,d2 double 2-part Julian Date (Notes 3,4)
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**
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** Returned (function value):
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** int status: +3 = both of next two
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** +2 = time is after end of day (Note 5)
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** +1 = dubious year (Note 6)
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** 0 = OK
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** -1 = bad year
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** -2 = bad month
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** -3 = bad day
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** -4 = bad hour
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** -5 = bad minute
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** -6 = bad second (<0)
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**
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** Notes:
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**
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** 1) scale identifies the time scale. Only the value "UTC" (in upper
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** case) is significant, and enables handling of leap seconds (see
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** Note 4).
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**
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** 2) For calendar conventions and limitations, see iauCal2jd.
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**
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** 3) The sum of the results, d1+d2, is Julian Date, where normally d1
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** is the Julian Day Number and d2 is the fraction of a day. In the
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** case of UTC, where the use of JD is problematical, special
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** conventions apply: see the next note.
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**
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** 4) JD cannot unambiguously represent UTC during a leap second unless
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** special measures are taken. The SOFA internal convention is that
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** the quasi-JD day represents UTC days whether the length is 86399,
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** 86400 or 86401 SI seconds. In the 1960-1972 era there were
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** smaller jumps (in either direction) each time the linear UTC(TAI)
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** expression was changed, and these "mini-leaps" are also included
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** in the SOFA convention.
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**
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** 5) The warning status "time is after end of day" usually means that
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** the sec argument is greater than 60.0. However, in a day ending
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** in a leap second the limit changes to 61.0 (or 59.0 in the case
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** of a negative leap second).
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**
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** 6) The warning status "dubious year" flags UTCs that predate the
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** introduction of the time scale or that are too far in the future
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** to be trusted. See iauDat for further details.
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**
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** 7) Only in the case of continuous and regular time scales (TAI, TT,
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** TCG, TCB and TDB) is the result d1+d2 a Julian Date, strictly
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** speaking. In the other cases (UT1 and UTC) the result must be
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** used with circumspection; in particular the difference between
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** two such results cannot be interpreted as a precise time
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** interval.
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**
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** Called:
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** iauCal2jd Gregorian calendar to JD
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** iauDat delta(AT) = TAI-UTC
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** iauJd2cal JD to Gregorian calendar
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**
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** This revision: 2013 July 26
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**
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** SOFA release 2020-07-21
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**
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** Copyright (C) 2020 IAU SOFA Board. See notes at end.
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*/
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{
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int js, iy2, im2, id2;
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double dj, w, day, seclim, dat0, dat12, dat24, dleap, time;
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/* Today's Julian Day Number. */
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js = iauCal2jd(iy, im, id, &dj, &w);
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if ( js ) return js;
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dj += w;
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/* Day length and final minute length in seconds (provisional). */
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day = DAYSEC;
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seclim = 60.0;
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/* Deal with the UTC leap second case. */
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if ( ! strcmp(scale,"UTC") ) {
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/* TAI-UTC at 0h today. */
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js = iauDat(iy, im, id, 0.0, &dat0);
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if ( js < 0 ) return js;
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/* TAI-UTC at 12h today (to detect drift). */
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js = iauDat(iy, im, id, 0.5, &dat12);
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if ( js < 0 ) return js;
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/* TAI-UTC at 0h tomorrow (to detect jumps). */
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js = iauJd2cal ( dj, 1.5, &iy2, &im2, &id2, &w);
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if ( js ) return js;
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js = iauDat(iy2, im2, id2, 0.0, &dat24);
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if ( js < 0 ) return js;
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/* Any sudden change in TAI-UTC between today and tomorrow. */
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dleap = dat24 - (2.0*dat12 - dat0);
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/* If leap second day, correct the day and final minute lengths. */
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day += dleap;
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if ( ihr == 23 && imn == 59 ) seclim += dleap;
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/* End of UTC-specific actions. */
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}
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/* Validate the time. */
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if ( ihr >= 0 && ihr <= 23 ) {
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if ( imn >= 0 && imn <= 59 ) {
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if ( sec >= 0 ) {
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if ( sec >= seclim ) {
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js += 2;
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}
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} else {
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js = -6;
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}
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} else {
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js = -5;
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}
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} else {
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js = -4;
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}
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if ( js < 0 ) return js;
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/* The time in days. */
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time = ( 60.0 * ( (double) ( 60 * ihr + imn ) ) + sec ) / day;
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/* Return the date and time. */
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*d1 = dj;
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*d2 = time;
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/* Status. */
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return js;
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/*----------------------------------------------------------------------
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**
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** Copyright (C) 2020
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** Standards Of Fundamental Astronomy Board
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** of the International Astronomical Union.
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**
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** =====================
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** SOFA Software License
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** =====================
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**
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** NOTICE TO USER:
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**
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** BY USING THIS SOFTWARE YOU ACCEPT THE FOLLOWING SIX TERMS AND
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** CONDITIONS WHICH APPLY TO ITS USE.
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**
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** 1. The Software is owned by the IAU SOFA Board ("SOFA").
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**
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** 2. Permission is granted to anyone to use the SOFA software for any
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** purpose, including commercial applications, free of charge and
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** without payment of royalties, subject to the conditions and
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** restrictions listed below.
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**
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** 3. You (the user) may copy and distribute SOFA source code to others,
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** and use and adapt its code and algorithms in your own software,
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** on a world-wide, royalty-free basis. That portion of your
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** distribution that does not consist of intact and unchanged copies
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** of SOFA source code files is a "derived work" that must comply
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** with the following requirements:
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**
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** a) Your work shall be marked or carry a statement that it
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** (i) uses routines and computations derived by you from
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** software provided by SOFA under license to you; and
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** (ii) does not itself constitute software provided by and/or
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** endorsed by SOFA.
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**
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** b) The source code of your derived work must contain descriptions
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** of how the derived work is based upon, contains and/or differs
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** from the original SOFA software.
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**
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** c) The names of all routines in your derived work shall not
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** include the prefix "iau" or "sofa" or trivial modifications
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** thereof such as changes of case.
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**
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** d) The origin of the SOFA components of your derived work must
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** not be misrepresented; you must not claim that you wrote the
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** original software, nor file a patent application for SOFA
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** software or algorithms embedded in the SOFA software.
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**
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** e) These requirements must be reproduced intact in any source
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** distribution and shall apply to anyone to whom you have
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** granted a further right to modify the source code of your
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** derived work.
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**
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** Note that, as originally distributed, the SOFA software is
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** intended to be a definitive implementation of the IAU standards,
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** and consequently third-party modifications are discouraged. All
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** variations, no matter how minor, must be explicitly marked as
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** such, as explained above.
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**
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** 4. You shall not cause the SOFA software to be brought into
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** disrepute, either by misuse, or use for inappropriate tasks, or
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** by inappropriate modification.
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**
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** 5. The SOFA software is provided "as is" and SOFA makes no warranty
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** as to its use or performance. SOFA does not and cannot warrant
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** the performance or results which the user may obtain by using the
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** SOFA software. SOFA makes no warranties, express or implied, as
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** to non-infringement of third party rights, merchantability, or
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** fitness for any particular purpose. In no event will SOFA be
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** liable to the user for any consequential, incidental, or special
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** damages, including any lost profits or lost savings, even if a
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** SOFA representative has been advised of such damages, or for any
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** claim by any third party.
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**
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** 6. The provision of any version of the SOFA software under the terms
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** and conditions specified herein does not imply that future
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** versions will also be made available under the same terms and
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** conditions.
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*
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** In any published work or commercial product which uses the SOFA
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** software directly, acknowledgement (see www.iausofa.org) is
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** appreciated.
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**
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** Correspondence concerning SOFA software should be addressed as
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** follows:
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**
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** By email: sofa@ukho.gov.uk
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** By post: IAU SOFA Center
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** HM Nautical Almanac Office
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** UK Hydrographic Office
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** Admiralty Way, Taunton
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** Somerset, TA1 2DN
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** United Kingdom
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**
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**--------------------------------------------------------------------*/
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}
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