; $Id: julday.pro,v 1.20 2004/01/21 15:54:55 scottm Exp $ ; ; Copyright (c) 1988-2004, Research Systems, Inc. All rights reserved. ; Unauthorized reproduction prohibited. ;+ ; NAME: ; JULDAY ; ; PURPOSE: ; Calculate the Julian Day Number for a given month, day, and year. ; This is the inverse of the library function CALDAT. ; See also caldat, the inverse of this function. ; ; CATEGORY: ; Misc. ; ; CALLING SEQUENCE: ; Result = JULDAY([[[[Month, Day, Year], Hour], Minute], Second]) ; ; INPUTS: ; MONTH: Number of the desired month (1 = January, ..., 12 = December). ; ; DAY: Number of day of the month. ; ; YEAR: Number of the desired year.Year parameters must be valid ; values from the civil calendar. Years B.C.E. are represented ; as negative integers. Years in the common era are represented ; as positive integers. In particular, note that there is no ; year 0 in the civil calendar. 1 B.C.E. (-1) is followed by ; 1 C.E. (1). ; ; HOUR: Number of the hour of the day. ; ; MINUTE: Number of the minute of the hour. ; ; SECOND: Number of the second of the minute. ; ; Note: Month, Day, Year, Hour, Minute, and Second can all be arrays. ; The Result will have the same dimensions as the smallest array, or ; will be a scalar if all arguments are scalars. ; ; OPTIONAL INPUT PARAMETERS: ; Hour, Minute, Second = optional time of day. ; ; OUTPUTS: ; JULDAY returns the Julian Day Number (which begins at noon) of the ; specified calendar date. If Hour, Minute, and Second are not specified, ; then the result will be a long integer, otherwise the result is a ; double precision floating point number. ; ; COMMON BLOCKS: ; None. ; ; SIDE EFFECTS: ; None. ; ; RESTRICTIONS: ; Accuracy using IEEE double precision numbers is approximately ; 1/10000th of a second, with higher accuracy for smaller (earlier) ; Julian dates. ; ; MODIFICATION HISTORY: ; Translated from "Numerical Recipies in C", by William H. Press, ; Brian P. Flannery, Saul A. Teukolsky, and William T. Vetterling. ; Cambridge University Press, 1988 (second printing). ; ; AB, September, 1988 ; DMS, April, 1995, Added time of day. ; CT, April 2000, Now accepts vectors or scalars. ;- ; function JULDAY, MONTH, DAY, YEAR, Hour, Minute, Second COMPILE_OPT idl2 ON_ERROR, 2 ; Return to caller if errors ; Gregorian Calander was adopted on Oct. 15, 1582 ; skipping from Oct. 4, 1582 to Oct. 15, 1582 GREG = 2299171L ; incorrect Julian day for Oct. 25, 1582 ; Process the input, if all are missing, use todays date. NP = n_params() IF (np EQ 0) THEN RETURN, SYSTIME(/JULIAN) IF (np LT 3) THEN MESSAGE, 'Incorrect number of arguments.' ; Find the dimensions of the Result: ; 1. Find all of the input arguments that are arrays (ignore scalars) ; 2. Out of the arrays, find the smallest number of elements ; 3. Find the dimensions of the smallest array ; Step 1: find all array arguments nDims = [SIZE(month,/N_DIMENSIONS), SIZE(day,/N_DIMENSIONS), $ SIZE(year,/N_DIMENSIONS), SIZE(hour,/N_DIMENSIONS), $ SIZE(minute,/N_DIMENSIONS), SIZE(second,/N_DIMENSIONS)] arrays = WHERE(nDims GE 1) nJulian = 1L ; assume everything is a scalar IF (arrays[0] GE 0) THEN BEGIN ; Step 2: find the smallest number of elements nElement = [N_ELEMENTS(month), N_ELEMENTS(day), $ N_ELEMENTS(year), N_ELEMENTS(hour), $ N_ELEMENTS(minute), N_ELEMENTS(second)] nJulian = MIN(nElement[arrays], whichVar) ; step 3: find dimensions of the smallest array CASE arrays[whichVar] OF 0: julianDims = SIZE(month,/DIMENSIONS) 1: julianDims = SIZE(day,/DIMENSIONS) 2: julianDims = SIZE(year,/DIMENSIONS) 3: julianDims = SIZE(hour,/DIMENSIONS) 4: julianDims = SIZE(minute,/DIMENSIONS) 5: julianDims = SIZE(second,/DIMENSIONS) ENDCASE ENDIF d_Second = 0d ; defaults d_Minute = 0d d_Hour = 0d ; convert all Arguments to appropriate array size & type SWITCH np OF ; use switch so we fall thru all arguments... 6: d_Second = (SIZE(second,/N_DIMENSIONS) GT 0) ? $ second[0:nJulian-1] : second 5: d_Minute = (SIZE(minute,/N_DIMENSIONS) GT 0) ? $ minute[0:nJulian-1] : minute 4: d_Hour = (SIZE(hour,/N_DIMENSIONS) GT 0) ? $ hour[0:nJulian-1] : hour 3: BEGIN ; convert m,d,y to type LONG L_MONTH = (SIZE(month,/N_DIMENSIONS) GT 0) ? $ LONG(month[0:nJulian-1]) : LONG(month) L_DAY = (SIZE(day,/N_DIMENSIONS) GT 0) ? $ LONG(day[0:nJulian-1]) : LONG(day) L_YEAR = (SIZE(year,/N_DIMENSIONS) GT 0) ? $ LONG(year[0:nJulian-1]) : LONG(year) END ENDSWITCH min_calendar = -4716 max_calendar = 5000000 minn = MIN(l_year, MAX=maxx) IF (minn LT min_calendar) OR (maxx GT max_calendar) THEN MESSAGE, $ 'Value of Julian date is out of allowed range.' if (MAX(L_YEAR eq 0) NE 0) then message, $ 'There is no year zero in the civil calendar.' bc = (L_YEAR LT 0) L_YEAR = TEMPORARY(L_YEAR) + TEMPORARY(bc) inJanFeb = (L_MONTH LE 2) JY = L_YEAR - inJanFeb JM = L_MONTH + (1b + 12b*TEMPORARY(inJanFeb)) JUL = floor(365.25d * JY) + floor(30.6001d*TEMPORARY(JM)) + L_DAY + 1720995L ; Test whether to change to Gregorian Calandar. IF (MIN(JUL) GE GREG) THEN BEGIN ; change all dates JA = long(0.01d * TEMPORARY(JY)) JUL = TEMPORARY(JUL) + 2L - JA + long(0.25d * JA) ENDIF ELSE BEGIN gregChange = WHERE(JUL ge GREG, ngreg) IF (ngreg GT 0) THEN BEGIN JA = long(0.01d * JY[gregChange]) JUL[gregChange] = JUL[gregChange] + 2L - JA + long(0.25d * JA) ENDIF ENDELSE ; hour,minute,second? IF (np GT 3) THEN BEGIN ; yes, compute the fractional Julian date ; Add a small offset so we get the hours, minutes, & seconds back correctly ; if we convert the Julian dates back. This offset is proportional to the ; Julian date, so small dates (a long, long time ago) will be "more" accurate. eps = (MACHAR(/DOUBLE)).eps eps = eps*ABS(jul) > eps ; For Hours, divide by 24, then subtract 0.5, in case we have unsigned ints. jul = TEMPORARY(JUL) + ( (TEMPORARY(d_Hour)/24d - 0.5d) + $ TEMPORARY(d_Minute)/1440d + TEMPORARY(d_Second)/86400d + eps ) ENDIF ; check to see if we need to reform vector to array of correct dimensions IF (N_ELEMENTS(julianDims) GT 1) THEN $ JUL = REFORM(TEMPORARY(JUL), julianDims) RETURN, jul END