Convert true Julian day to calendar date

INTERFACE:

    subroutine calendar_date(julian,yyyy,mm,dd)

DESCRIPTION:

Converts a Julian day to a calendar date -- year, month and day. Based on a similar routine in Numerical Recipes.

USES:

    IMPLICIT NONE

INPUT PARAMETERS:

    integer                             :: julian

OUTPUT PARAMETERS:

    integer                             :: yyyy,mm,dd

REVISION HISTORY:

    Original author(s): Karsten Bolding & Hans Burchard