Crigou

For those who are using the NGS Online Inverse Geodesic Calculator: http://www.ngs.noaa.gov/cgi-bin/Inv_Fwd/inverse2.prl be careful. Especially between two near-antipodal locations, the computed distance shows an error of some tens of kilometres !!! The origin of the numeric trouble was identified long time ago by Thaddeus Vincenty (page 92): http://www.ngs.noaa.gov/PUBS_LIB/inverse.pdf In any case, it is preferrable to use the reliable and very accurate online calculator by Charles Karney: http://geographiclib.sourceforge.net/cgi-bin/Geod

For those who are using the NGS Online Inverse Geodesic Calculator: http://www.ngs.noaa.gov/cgi-bin/Inv_Fwd/inverse2.prl be careful. Especially between two near-antipodal locations, the computed distance shows an error of some tens of kilometres !!! The origin of the numeric trouble was identified long time ago by Thaddeus Vincenty (page 92): http://www.ngs.noaa.gov/PUBS_LIB/inverse.pdf In any case, it is preferrable to use the reliable and very accurate online calculator by Charles Karney: http://geographiclib.sourceforge.net/cgi-bin/Geod