NoSQL operator: julian

Translates selected date columns from calendar to julian format
for mathematical computations.

Usage: julian [options] [column ...]

Options:
    --input (-i) 'file'
      Read input from 'file' instead of STDIN.

    --output (-o) 'file'
      Write output to 'file' instead of STDOUT.

    --help (-h)
      Display this help text.

    --no-header (-N)
      Remove header from output.

    --last (-l)
      If the input table contains duplicated column names
      pick the last occurrence of each. The default is to
      pick the first one. This is sometimes useful after
      the 'jointable' operator.

Notes:

Translates date values in the specified columns into their "Julian"
value. The Julian date (JD) is a continuous count of days from
1 January 4713 BC (= -4712 January 1), Greenwich mean noon (= 12h UT).
For example, AD 1978 January 1, 0h UT is JD 2443509.5 and
AD 1978 July 21, 15h UT, is JD 2443711.125. Note that Julian days
start at noon, while Gregorian days start at midnight.

This program will perform the translation only if the value in
the specified column(s) has a recognized format, that is:

[yy]yymmdd   = Computer format
[yy]yy-mm-dd = ISO format
dd.mm.[yy]yy = European format
mm/dd/[yy]yy = U.S. format

If [yy] is not specified it defaults to 20.

Curently the input date precision is limited to the day, although
the program internally could also handle hours, minutes and seconds.
This capability may be exploited in a future release. For the moment
an input date of yyyymmdd is implicitly treated as yyyymmdd000000,
i.e. the "midday" of a julian day.

References:

1. http://aa.usno.navy.mil/faq/docs/JD_Formula.html

2. Fliegel, H. F. and van Flandern, T. C. (1968).
   Communications of the ACM, Vol. 11, No. 10 (October, 1968).