anchor.diff:          !
           !------------------------------------------------------------
           else if (this%calendar==NOLEAP) then
  +
               year = floor((mjd + (this%month_start(this%month_zero)-1) + (this%day_zero-1) + this%hour_zero/24.0) / 365)
               day_fraction = mjd - year*365+1 + (this%month_start(this%month_zero)-1) + (this%day_zero-1) + this%hour_zero/24.0
               month = 1
  
positive.code:             date_to_mjd = date_to_mjd - gregorian_julian_day(this%year_zero, this%month_zero, this%day_zero, this%hour_zero, 0, 0)
  
          else if (this%calendar==NOLEAP) then
              date_to_mjd = (year-this%year_zero)*365 + this%month_start(month)-1 + day-1 + (hour + (minute+second/60d+0)/60d+0)/24d+0
          else if (this%calendar==THREESIXTY) then
              date_to_mjd = (year-this%year_zero)*360 + this%month_start(month)-1 + day-1 + (hour + (minute+second/60d+0)/60d+0)/24d+0
          end if
  
      end function date_to_mjd
  
negative.code: 
              day = floor(day_fraction - this%month_start(month)) + 1
              year = year + this%year_zero
              mjd = mjd - this%hour_zero/24.0
          end if
  
          !------------------------------------------------------------
  