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. KEYWORD PARAMETERS: NDAYSPM: for using a calendar with fixed number of days per months. defaut value of NDAYSPM=30 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: cm_4cal 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. Eric Guilyardi, June 1999 Added key_work ndayspm for fixed number of days per months + change to accept year 0 Sebastien Masson, Aug. 2003 fix bug for negative and large values of month values eg. julday(349,1,1970) CT, April 2000, Now accepts vectors or scalars.