int eraTdbtcb	(	double	tdb1,
		double	tdb2,
		double *	tcb1,
		double *	tcb2
	)

Definition at line 3 of file tdbtcb.c.

References ERFA_DAYSEC, ERFA_DJM0, ERFA_DJM77, ERFA_ELB, ERFA_TDB0, and ERFA_TTMTAI.

Referenced by t_tdbtcb().

{

/* 1977 Jan 1 00:00:32.184 TT, as two-part JD */
   static const double t77td = ERFA_DJM0 + ERFA_DJM77;
   static const double t77tf = ERFA_TTMTAI/ERFA_DAYSEC;

/* TDB (days) at TAI 1977 Jan 1.0 */
   static const double tdb0 = ERFA_TDB0/ERFA_DAYSEC;

/* TDB to TCB rate */
   static const double elbb = ERFA_ELB/(1.0-ERFA_ELB);

   double d, f;

/* Result, preserving date format but safeguarding precision. */
   if ( tdb1 > tdb2 ) {
      d = t77td - tdb1;
      f  = tdb2 - tdb0;
      *tcb1 = tdb1;
      *tcb2 = f - ( d - ( f - t77tf ) ) * elbb;
   } else {
      d = t77td - tdb2;
      f  = tdb1 - tdb0;
      *tcb1 = f + ( d - ( f - t77tf ) ) * elbb;
      *tcb2 = tdb2;
   }

/* Status (always OK). */
   return 0;

}

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