c
c     ****************************
c     ***  Subroutine JLcMJL   ***
c     ***  1984/12/06/09-45    ***
c     ****************************
c
      Subroutine JLcMJL(jl,fjl,  mjl,fmjl)
***********************************************************************
*                                                                     *
*     Purpose:  Given the Julian date in days and fraction of         *
*               days (jl, fjl).                                       *
*                                                                     *
*               Compute the modified Julian date in days plus         *
*               fractional days (mjl, fmjl).                          *
*                                                                     *
*               The Julian date is a continuous count of days and     *
*               fractional days from -4712 b.C. january 1 at          *
*               0.5 hours UT.                                         * 
*               The Julian date 2415385.5 is that for jan. 1, 1901    *
*               at zero hours. This program is valid between then     *
*                                                                     *
*               The modified Julian date is obtained from the         *
*               Julian date by computing                              *
*               (mjl, fmjl) = (jl-2400000, fjl-0.5)                   *
*                                                                     *
*               This program is valid between jan. 1, 1901 and        *
*               dec. 31, 2099 at midnite.                             *
*                                                                     *
*                                                                     *
*     Parameters    Type     I/O      Function                        *
*                                                                     *
*     jl            i*8       I       days of Julian date             *
*     fjl           r*8       I       fractional part of              *
*                                     days of Julian date             *
*                                                                     *
*     mjl           i*4       O       days of modified Julian         *
*                                     date                            *
*     fmjl          r*8       O       fractional part of days         *
*                                     of modidied Julian date         *
*                                                                     *
*                                                                     *
*     Examples                                                        *
*                                                                     *
*     Input: jl = 2445700,  fjl = 0.4999898548239471                  *
*     Represents: 1983/12/31/23/59/59.1234567890                      *
*     Output: mjl = 45699, fmjl = 0.9999898548239472                  *
*                                                                     *
*     Input: jl = 2445700,  fjl = 0.5000000000000000                  *
*     Represents: 1984/01/01/00/00/00.0                               *
*     Output: mjl = 45700, fmjl = 0.0000000000000000                  *
*                                                                     *
*     Input: jl = 2445700,  fjl = 0.5000115740740741                  *
*     Represents: 1984/01/01/00/00/01.0000000000                      *
*     Output: mjl = 45700, fmjl = 0.0000115740740740                  *
*                                                                     *
*     Input: jl = 2445981,  fjl = 0.1459736511202432                  *
*     Represents: 1984/10/07/15/30/12.1234567890                      *
*     Output: mjl = 45980,  fjl = 0.6459736511202432                  *
*                                                                     *
*                                                                     *
*                             B. Hofmann-Wellenhof, B. Remondi        *
*                                                                     *
***********************************************************************
      implicit real*8(a-h,o-z)
c
c     Input data test.
c
      if((jl+fjl) .lt. (2415385.+.5)  .or.  (jl+fjl) .gt. (2488069.+.5))
     +  stop
     +  '  JLcMJL:  "jl+fjl"  must be  2415385.5 <= jl+fjl <= 2488069.5'
      if(jl .lt. 2415385  .or.  jl .gt. 2488069)
     +  stop '  JLcMJL:  "jl"  must be  2415385 <= jl <= 2488069'
      if(fjl .lt. 0.d0  .or.  fjl .ge. 1.d0)
     +  stop '  JLcMJL:  "fjl"  must be  0.0 <= fjl < 1.0'
c
      mjl = jl - 2400000
      fmjl = fjl - 0.5d0
      if(fmjl .ge. 0.d0) return
      fmjl = fmjl + 1.d0
      mjl = mjl - 1
      return
c
c     End of Subroutine JLcMJL
c
c     *****************************************************************
      end