c date: converts from calendar to day number and back.
c*******************************************
       logical*1 truth
 55    call print('enter year (eg: 96)')
       read (*,*)iy
       if(truth('want calendar date?'))then
       iway=0
       call print('enter day number: (eg: 123)')
       read(*,*)jd
       call julian(iy,im,id,jd,iway)
       write(*,22)iy,im,id
 22    format('year: ',i2.2,' month: ',i2.2,' day: ',i2.2)
       else
       iway=1
       call print('enter month and day: (eg: 0112)')
       read(*,'(2(i2.2))')im,id
       call julian(iy,im,id,jd,iway)
       write(*,33)jd
 33    format('Day number is:',i3)
       endif
       if(truth('again?'))goto 55
       stop
       end 
       subroutine julian(iy,im,id,jd,iway)
c
c      gives day number
c
       integer mo(12)
       data mo/31,28,31,30,31,30,31,31,30,31,30,31/
       leap=0
       if(iy.eq.80.or.iy.eq.84.or.iy.eq.88.or.iy.eq.92)leap=1
       if(iy.eq.96)leap=1
       mo(2)=28+leap
c
       if(iway.eq.1)then    ! go from calendar to day number
       jd=0
c
       if(im.eq.1)then
       goto 5
       else
       do 2 i=1,im-1
       jd=jd+mo(i)
 2     continue
       endif
c
 5     jd=jd+id
       return
       endif
c
       if(iway.eq.0)then
c inverse transform
       sum=0
       do 4 i=1,12
       sum=sum+mo(i)
       itest=jd-sum
       if(itest.le.0)then
       im=i
       goto 66
       endif
 4     continue
 66    continue
       if(im.eq.1)id=jd
       if (im.ne.1)id=jd-sum+mo(im)
       endif
       return
       end