;+
; NAME		month_day.pro
;
; PURPOSE	Compute month & day corresponding to a Day-Of-Year.
;
; AUTHOR	Alice Lecinski   HAO/NCAR   mon_day.c
;
; HISTORY	Andrew L. Stanger   HAO/NCAR   19 Nov 2002
;		19 Nov 2002: Convert from C to IDL.
;
;-

PRO month_day, doy, year, month, day

    day_tab = INTARR (13, 2)

    day_tab [*, 0] = [0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]
    day_tab [*, 1] = [0, 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]

    leap = (y4 EQ 0) AND (y100 NE 0) OR (y400 EQ 0)

    ii = 1
    WHILE (doy GT day_tab [ii, leap]) DO	$
    BEGIN
	doy = doy - day_tab [ii, leap]
	ii = ii + 1
    END

    month = ii ;
    day   = doy ;
END