julian.f

Go to the documentation of this file.

      SUBROUTINE julian(TIN,TOUT)
C  VERSION OF 4/1/85
C  PURPOSE
C    COMPUTES JULIAN DATE WHEN GIVEN CALENDER DATE AND TIME
C  INPUT
C    TIN(1) = CALENDER DATE, YYYYMMDD.
C       (2) = CALENDER TIME, HHMMSS.SSSS
C  OUTPUT
C    TOUT   = JULIAN DATE (DAYS)
C  CALL SUBROUTINES
C    NONE
C  REFERENCES
C    JPL EM 312/87-153, 20 APRIL 1987
C  ANALYSIS
C    J. H. KWOK
C  PROGRAMMER
C    J. H. KWOK
C  PROGRAM MODIFICATIONS
C    NONE
C  COMMENTS
C    NONE
C
      IMPLICIT DOUBLE PRECISION (a-h,o-z)
      dimension tin(2)
      DATA d0,d1,d2,d3,d4,d5/2415020.5d0,1.d-4,1.d-2,24.d0,1.44d3
     1,8.64d4/
C
C  THIS IS THE JULIAN DATE FOR 19000101
C
      tout=d0
C
      iy=int(tin(1)*d1-1.9d3)
      im=int(tin(1)*d2-1.9d5)-iy*100
      id=int(tin(1)-1.9d7)-iy*10000-im*100
      ihour=int(tin(2)*d1)
      imin=int(tin(2)*d2)-ihour*100
      sec=tin(2)-ihour*10000-imin*100
      jd=iy*365+(iy-1)/4
      im1=im-1
      IF (im1.EQ.0) GO TO 12
      GO TO (1,2,3,4,5,6,7,8,9,10,11),im1
    1 jd=jd+31
      GO TO 12
    2 jd=jd+59
      GO TO 12
    3 jd=jd+90
      GO TO 12
    4 jd=jd+120
      GO TO 12
    5 jd=jd+151
      GO TO 12
    6 jd=jd+181
      GO TO 12
    7 jd=jd+212
      GO TO 12
    8 jd=jd+243
      GO TO 12
    9 jd=jd+273
      GO TO 12
   10 jd=jd+304
      GO TO 12
   11 jd=jd+334
   12 CONTINUE
      IF (iy/4*4-iy.EQ.0.AND.im.GT.2) jd=jd+1
      jd=jd+id-1
      tout=tout+jd+ihour/d3+imin/d4+sec/d5
      RETURN
      END