;* day_of_year.pro
;* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
;* IDL programming language.
;* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
;*

;/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

FUNCTION day_of_year, 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]



y4   = year MOD 4
y100 = year MOD 100
y400 = year MOD 400

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

;print, 'year: ', year, '   leap: ', leap

FOR i = 1, month-1 DO				$
    BEGIN
        day = day + day_tab [i, leap];
    END

RETURN, day
END

;/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */