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#include "erfa.h"
int eraUtctai(double utc1, double utc2, double *tai1, double *tai2)
/*
** - - - - - - - - - -
** e r a U t c t a i
** - - - - - - - - - -
**
** Time scale transformation: Coordinated Universal Time, UTC, to
** International Atomic Time, TAI.
**
** Given:
** utc1,utc2 double UTC as a 2-part quasi Julian Date (Notes 1-4)
**
** Returned:
** tai1,tai2 double TAI as a 2-part Julian Date (Note 5)
**
** Returned (function value):
** int status: +1 = dubious year (Note 3)
** 0 = OK
** -1 = unacceptable date
**
** Notes:
**
** 1) utc1+utc2 is quasi Julian Date (see Note 2), apportioned in any
** convenient way between the two arguments, for example where utc1
** is the Julian Day Number and utc2 is the fraction of a day.
**
** 2) JD cannot unambiguously represent UTC during a leap second unless
** special measures are taken. The convention in the present
** function is that the 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 ERFA convention.
**
** 3) 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 eraDat for further details.
**
** 4) The function eraDtf2d converts from calendar date and time of day
** into 2-part Julian Date, and in the case of UTC implements the
** leap-second-ambiguity convention described above.
**
** 5) The returned TAI1,TAI2 are such that their sum is the TAI Julian
** Date.
**
** Called:
** eraJd2cal JD to Gregorian calendar
** eraDat delta(AT) = TAI-UTC
** eraCal2jd Gregorian calendar to JD
**
** References:
**
** McCarthy, D. D., Petit, G. (eds.), IERS Conventions (2003),
** IERS Technical Note No. 32, BKG (2004)
**
** Explanatory Supplement to the Astronomical Almanac,
** P. Kenneth Seidelmann (ed), University Science Books (1992)
**
** Copyright (C) 2013-2016, NumFOCUS Foundation.
** Derived, with permission, from the SOFA library. See notes at end of file.
*/
{
int big1;
int iy, im, id, j, iyt, imt, idt;
double u1, u2, fd, dat0, dat12, w, dat24, dlod, dleap, z1, z2, a2;
/* Put the two parts of the UTC into big-first order. */
big1 = ( utc1 >= utc2 );
if ( big1 ) {
u1 = utc1;
u2 = utc2;
} else {
u1 = utc2;
u2 = utc1;
}
/* Get TAI-UTC at 0h today. */
j = eraJd2cal(u1, u2, &iy, &im, &id, &fd);
if ( j ) return j;
j = eraDat(iy, im, id, 0.0, &dat0);
if ( j < 0 ) return j;
/* Get TAI-UTC at 12h today (to detect drift). */
j = eraDat(iy, im, id, 0.5, &dat12);
if ( j < 0 ) return j;
/* Get TAI-UTC at 0h tomorrow (to detect jumps). */
j = eraJd2cal(u1+1.5, u2-fd, &iyt, &imt, &idt, &w);
if ( j ) return j;
j = eraDat(iyt, imt, idt, 0.0, &dat24);
if ( j < 0 ) return j;
/* Separate TAI-UTC change into per-day (DLOD) and any jump (DLEAP). */
dlod = 2.0 * (dat12 - dat0);
dleap = dat24 - (dat0 + dlod);
/* Remove any scaling applied to spread leap into preceding day. */
fd *= (ERFA_DAYSEC+dleap)/ERFA_DAYSEC;
/* Scale from (pre-1972) UTC seconds to SI seconds. */
fd *= (ERFA_DAYSEC+dlod)/ERFA_DAYSEC;
/* Today's calendar date to 2-part JD. */
if ( eraCal2jd(iy, im, id, &z1, &z2) ) return -1;
/* Assemble the TAI result, preserving the UTC split and order. */
a2 = z1 - u1;
a2 += z2;
a2 += fd + dat0/ERFA_DAYSEC;
if ( big1 ) {
*tai1 = u1;
*tai2 = a2;
} else {
*tai1 = a2;
*tai2 = u1;
}
/* Status. */
return j;
}
/*----------------------------------------------------------------------
**
**
** Copyright (C) 2013-2016, NumFOCUS Foundation.
** All rights reserved.
**
** This library is derived, with permission, from the International
** Astronomical Union's "Standards of Fundamental Astronomy" library,
** available from http://www.iausofa.org.
**
** The ERFA version is intended to retain identical functionality to
** the SOFA library, but made distinct through different function and
** file names, as set out in the SOFA license conditions. The SOFA
** original has a role as a reference standard for the IAU and IERS,
** and consequently redistribution is permitted only in its unaltered
** state. The ERFA version is not subject to this restriction and
** therefore can be included in distributions which do not support the
** concept of "read only" software.
**
** Although the intent is to replicate the SOFA API (other than
** replacement of prefix names) and results (with the exception of
** bugs; any that are discovered will be fixed), SOFA is not
** responsible for any errors found in this version of the library.
**
** If you wish to acknowledge the SOFA heritage, please acknowledge
** that you are using a library derived from SOFA, rather than SOFA
** itself.
**
**
** TERMS AND CONDITIONS
**
** Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions
** are met:
**
** 1 Redistributions of source code must retain the above copyright
** notice, this list of conditions and the following disclaimer.
**
** 2 Redistributions in binary form must reproduce the above copyright
** notice, this list of conditions and the following disclaimer in
** the documentation and/or other materials provided with the
** distribution.
**
** 3 Neither the name of the Standards Of Fundamental Astronomy Board,
** the International Astronomical Union nor the names of its
** contributors may be used to endorse or promote products derived
** from this software without specific prior written permission.
**
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
** FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
** COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
** BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
** CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
** ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
** POSSIBILITY OF SUCH DAMAGE.
**
*/
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