Updates for SOFA Release 16 : 2020 July 21 - - - - - - - - - - - - - - - - - - - - - - Summary of Changes ------------------ The changes fall into the following categories: 1. Correction of a sign in routine P06E. 2. Correction in the ANSI C macro function dnint in the include file sofam.h, to improve rounding. 3. Improvements in precision and rounding (see 2 and 3 below). 4. Miscellaneous typographical corrections and improvements to various other documents. + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + FORTRAN 77 Library ------------------ 1. iau_P06E Correction. The series are taken from Table 1 of Hilton, J. et al., 2006, Celest. Mech. Dyn. Astron. 94, 351., and it has been discovered that the one for general precession, p_A, had the wrong sign for the t^5 coefficient. The error in the paper has been corrected in the SOFA code. The correct value is -0.0000000383 arcsec. (Even after five centuries the error would be lower than 250 microarcsec.) 2. iau_PB06 Improvements in the method of decomposing the rotation matrix by ensuring that angles near zero are preferred. 3. iau_JD2CAL Improvements by ensuring precision is not lost when iau_JDCALF splitting date and time. 4. iau_DAT Release year updated. 5. t_sofa_f.for Updated due to the correction in iau_P06E. 6. iau_FK524 Minor corrections/improvements to the documentation. iau_FW2M iau_GMST82 iau_TRXP iau_XYS00A + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + ANSI C Library -------------- 1. iauP06e Correction. The series are taken from Table 1 of Hilton, J. et al., 2006, Celest. Mech. Dyn. Astron. 94, 351., and it has been discovered that the one for general precession, p_A, had the wrong sign for the t^5 coefficient. The error in the paper has been corrected in the SOFA code. The correct value is -0.0000000383 arcsec. (Even after five centuries the error would be lower than 250 microarcsec.) 2. sofam.h Correction to dnint(A). The existing dnint macro could incorrectly round numbers just over -0.5 and just under +0.5 due to the loss of precision when calculating ceil(A-0.5) or floor(A+0.5). A preliminary test for |A|<0.5 has been added to ensure that such numbers always round to zero. As none of the SOFA C functions depend critically on perfect rounding, the change is unlikely to affect user applications noticeably, though critical round-trip tests may see an improvement. 3. iauPb06 Improvements in the method of decomposing the rotation matrix by ensuring that angles near zero are preferred. 4. iauJd2cal Improvements by ensuring precision is not lost when iauJdcalf splitting date and time. 5. iauDat Release year updated. 6. t_sofa_c.c Updated due to the correction in iauP06e. 7. iauA2af Minor corrections/improvements to the documentation. iauA2tf iauD2tf iauFk524 iauFw2m iauGmst82 iauTrxp iauXys00a + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + SOFA thanks all those who have reported the various issues that go + to ensuring the libraries and documentation are kept up-to-date and + relevant. + + End of updates + 2020 June 22 + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +