program darstellung
*---------------------------------------------------------------
*     Darstellung von Zahlen auf dem Computer
*     gfortran -fno-range-check darstellung.f -o darstellung
*---------------------------------------------------------------
      implicit none
*
      integer*1  I1  
      integer*4  i,I4,IR4
*
      real*4     R4
      real*8     R8
      EQUIVALENCE(R4,IR4)       ! einer der gefährlichsten FORTRAN-Befehle
*
      complex*16 C16,D16,ui
*     
      character  Version*50
*
      ui     = DCMPLX(0.d0,1.d0)
      Version= '# darstellung 02 Juergen Schnack  03. 05. 2016'
*---------------------------------------------------------------
*
*     Version
*
      write(6,'(a)') Version
*---------------------------------------------------------------
*     result = IBITS (i, pos, len)
*     The rightmost (least significant) bit of i is in position 0
*
*     I1 integer*1 ist 1 byte = 8 bit lang
*
      write(6,'(a)') '# integer*1'

      I1 = 16
      write(6,'(i4,a)',advance="no") I1,' = '
      do i=7,0,-1
         write(6,'(i2)',advance="no") IBITS(I1,i,1)
      enddo
      write(6,*)

      I1 = 31
      write(6,'(i4,a)',advance="no") I1,' = '
      do i=7,0,-1
         write(6,'(i2)',advance="no") IBITS(I1,i,1)
      enddo
      write(6,*)

      I1 = 127
      write(6,'(i4,a)',advance="no") I1,' = '
      do i=7,0,-1
         write(6,'(i2)',advance="no") IBITS(I1,i,1)
      enddo
      write(6,*)

      I1 = -127
      write(6,'(i4,a)',advance="no") I1,' = '
      do i=7,0,-1
         write(6,'(i2)',advance="no") IBITS(I1,i,1)
      enddo
      write(6,*)

      I1 = 128
      write(6,'(i4,a)',advance="no") I1,' = '
      do i=7,0,-1
         write(6,'(i2)',advance="no") IBITS(I1,i,1)
      enddo
      write(6,*)

      I1 = -128
      write(6,'(i4,a)',advance="no") I1,' = '
      do i=7,0,-1
         write(6,'(i2)',advance="no") IBITS(I1,i,1)
      enddo
      write(6,*)

      I1 = 255
      write(6,'(i4,a)',advance="no") I1,' = '
      do i=7,0,-1
         write(6,'(i2)',advance="no") IBITS(I1,i,1)
      enddo
      write(6,*)

      I1 = -16
      write(6,'(i4,a)',advance="no") I1,' = '
      do i=7,0,-1
         write(6,'(i2)',advance="no") IBITS(I1,i,1)
      enddo
      write(6,*)

      I1 = 32768
      write(6,'(i4,a)',advance="no") I1,' = '
      do i=7,0,-1
         write(6,'(i2)',advance="no") IBITS(I1,i,1)
      enddo
      write(6,*)

*---------------------------------------------------------------
*     result = IBITS (i, pos, len)
*     The rightmost (least significant) bit of i is in position 0
*
*     I4 integer*4 ist 4 byte = 4x8 bits lang
*
      write(6,'(a)') '# integer*4'

      I4 = 16
      write(6,'(i4,a)',advance="no") I4,' = '
      do i=31,0,-1
         write(6,'(i2)',advance="no") IBITS(I4,i,1)
      enddo
      write(6,*)

      I4 = 31
      write(6,'(i4,a)',advance="no") I4,' = '
      do i=31,0,-1
         write(6,'(i2)',advance="no") IBITS(I4,i,1)
      enddo
      write(6,*)

      I4 = 127
      write(6,'(i4,a)',advance="no") I4,' = '
      do i=31,0,-1
         write(6,'(i2)',advance="no") IBITS(I4,i,1)
      enddo
      write(6,*)

      I4 = 128
      write(6,'(i4,a)',advance="no") I4,' = '
      do i=31,0,-1
         write(6,'(i2)',advance="no") IBITS(I4,i,1)
      enddo
      write(6,*)

      I4 = -127
      write(6,'(i4,a)',advance="no") I4,' = '
      do i=31,0,-1
         write(6,'(i2)',advance="no") IBITS(I4,i,1)
      enddo
      write(6,*)

      I4 = -128
      write(6,'(i4,a)',advance="no") I4,' = '
      do i=31,0,-1
         write(6,'(i2)',advance="no") IBITS(I4,i,1)
      enddo
      write(6,*)

      I4 = 255
      write(6,'(i4,a)',advance="no") I4,' = '
      do i=31,0,-1
         write(6,'(i2)',advance="no") IBITS(I4,i,1)
      enddo
      write(6,*)

      I4 = -16
      write(6,'(i4,a)',advance="no") I4,' = '
      do i=31,0,-1
         write(6,'(i2)',advance="no") IBITS(I4,i,1)
      enddo
      write(6,*)

*---------------------------------------------------------------
*
*     R4 real*4 (C: float) 4 byte = 4x8 bits lang
*
      write(6,'(a)') '# real*4'

      R4 = 1.0
      write(6,'(f15.6,a)',advance="no") R4,' = '
      do i=31,0,-1
         write(6,'(i2)',advance="no") IBITS(IR4,i,1)
      enddo
      write(6,*)

      R4 = -1.0
      write(6,'(f15.6,a)',advance="no") R4,' = '
      do i=31,0,-1
         write(6,'(i2)',advance="no") IBITS(IR4,i,1)
      enddo
      write(6,*)

      R4 = 0.5
      write(6,'(f15.6,a)',advance="no") R4,' = '
      do i=31,0,-1
         write(6,'(i2)',advance="no") IBITS(IR4,i,1)
      enddo
      write(6,*)

      R4 = 0.75
      write(6,'(f15.6,a)',advance="no") R4,' = '
      do i=31,0,-1
         write(6,'(i2)',advance="no") IBITS(IR4,i,1)
      enddo
      write(6,*)

      R4 = 1.d0/0.d0
      write(6,'(f15.6,a)',advance="no") R4,' = '
      do i=31,0,-1
         write(6,'(i2)',advance="no") IBITS(IR4,i,1)
      enddo
      write(6,*)

*---------------------------------------------------------------
*
*     FORTRAN beherrscht komplexe Zahlen!!!
*
      write(6,'(a)') '# complex*16'

      C16 = DCMPLX(1.0,1.0)
      D16 = DCMPLX(1.0,-1.0)
      write(6,*) 'C16 = ',C16
      write(6,*) 'D16 = ',D16
      write(6,*) 'C16 * D16 = ',C16 * D16

*---------------------------------------------------------------
*
*     Schluss
*
 9999 continue
      write(6,'(a)') '# Fertig!'

      stop
      end