id,summary,reporter,owner,description,type,status,priority,milestone,component,version,resolution,keywords,cc 2168,ST_Distance is not always commutative,realityexists,robe,"I've found a case where changing the order of operands for ST_Distance(geog) causes it to return slightly different results: {{{ SELECT ST_Distance('POINT(-40 46.167)'::geography, 'POINT(0 7.167)'::geography) - ST_Distance('POINT(0 7.167)'::geography, 'POINT(-40 46.167)'::geography); }}} returns 9.31322574615479e-010 on r10952, Windows x64, PostgreSQL 9.1.4 and 9.2.1. On 32-bit Linux it returns 0 as expected. This caused some odd behaviour in my application, which orders sets of points by their distance from each other - the result was different depending on the order in which points were considered. There's an easy workaround, of course - just round the results - but I can imagine other developers scratching their heads over this as well.",defect,closed,medium,PostGIS 2.0.4,postgis,master,fixed,,jkania