IW3JDN

The IW3JDN function computes julian day number.

USAGE:   II = IW3JDN(IYEAR,MONTH,IDAY)

   INPUT VARIABLES:
      IYEAR  ARG LIST  INTEGER   YEAR           ( 4 DIGITS)
      MONTH  ARG LIST  INTEGER   MONTH OF YEAR   (1 - 12)
      IDAY   ARG LIST  INTEGER   DAY OF MONTH    (1 - 31)
 
   OUTPUT VARIABLES:
      IW3JDN FUNTION   INTEGER   JULIAN DAY NUMBER

      For example:
               JAN. 1,1960 IS JULIAN DAY NUMBER 2436935
               JAN. 1,1987 IS JULIAN DAY NUMBER 2446797
 
REMARKS:
      Julian period was devised by Joseph Scaliger in 1582.
      Julian day number #1 started on Jan. 1,4713 B.C. Three major
      chronological cycles begin on the same day. A 28-year solar
      cycle, a 19-year luner cycle, a 15-year indiction cycle, used
      in ancient Rome to regulate taxes. It will take 7980 years
      to complete the period, the product of 28, 19, and 15.
      Scaliger named the period, date, and number after his father
      Julius (not after the Julian calendar). This seems to have
      caused a lot of confusion in text books. Scaliger name is
      spelled three different ways. Julian date and Julian day
      number are interchanged. A Julian date is used by astronomers
      to compute accurate time, It has a fraction. When truncated to
      an integer it is called an Julian day number. This function
      was in a letter to the editor of the communications of the acm
      volume 11 / number 10 / october 1968. The Julian day number
      can be converted to a year, month, day, day of week, day of
      year by calling subroutine W3FS26.

 


  
W3lib.tar
  
Library contains Fortran 90 decoder/encoder
   routines for GRIB edition 1. (Fortran90) 

   Date posted: 2/22/2007