NAME:
    jd2year
 PURPOSE: (one line)
    Convert Julian date to decimal year.
 DESCRIPTION:

 CATEGORY:
    Astronomy
 CALLING SEQUENCE:
    jd2year, jd, year
 INPUTS:
    jd     : Julian Date (double precision ONLY)
 OPTIONAL INPUT PARAMETERS:

 KEYWORD PARAMETERS:

 OUTPUTS:
    year   : Decimal year
 COMMON BLOCKS:

 SIDE EFFECTS:

 RESTRICTIONS:

 PROCEDURE:

 MODIFICATION HISTORY:
  1993/09/30, Written by Doug Loucks, Lowell Observatory.
  2010/12/06, MWB, changed to allow single precision floating point input.