On 16/01/2012 03:09, waldo kitty wrote: > > i'm needing to convert a "UTC epoch" date to a "standard time > string"... by that, i mean that i want to get something like > "2011-01-13 22:24:04" out of the "epoch" number 12013.9338171... > > the above "epoch" number is (supposedly) built like this... > > 12 == 2012 013 == 13th day of the year .9338171 * 24 == 22.4116104 > hours .4114104 * 60 == 24.696624 minutes > > and here's where it breaks on me because > > .696624 * 60 == 41.79744 seconds and that doesn't match the above > time string showing 04 seconds... that time string was built from > this "epoch" number (by another program) and i assume that it > followed this published formula for this format (which is for > satellite TLEs)... > > so, my question is this... is there an existing FPC routine that will > convert this (or a part of this) properly or do i need to play with > something to get it right? it is obvious that this is not a "unix > epoch"... i'm not sure how "normal" julian date epochs are > represented... > > i've looked through the docs on freepascal.org but none of them show > an number with which to compare... there's no links pointing to a > definition or example of a julian date or unix date or any such... > > help! please :/ >
See what Sven Barth said, for DateUtils but also as for seconds mismatch, may it be due to leap seconds ? http://en.wikipedia.org/wiki/Leap_second which actually shows that current TAI - UTC = 34 seconds (TAI = International Atomic Time) this actually is it: 41 - 34 = 7 (it's not 4 unfortunately but still close ?) (I guess satellite position is rather relative to TAI than UTC?) (Or some float calculation bug like http://en.wikipedia.org/wiki/Pentium_FDIV_bug (or some float-to-string representation problem)) Lukasz _______________________________________________ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
