program test_spacing 
  implicit none 
  real(4) :: r4 
  real(8) :: r8 
  integer(4) :: i4 
  real(8) :: esp, dig, rad 
  r8 = 1 
  do while ( r8 /= 0.0d0 ) 
   print*," Introdurre un numero reale:" 
   read(*,*) r8 
   esp = EXPONENT(r8) 
   dig = DIGITS(r8) 
   rad = RADIX(r8)
   print*," RRSPACING(",r8,") = ",RRSPACING(r8), &
          abs(r8*(rad**(-esp)))*rad**dig
   print*," SPACING(",r8,") = ",SPACING(r8), &
          rad**(esp-dig)
   r4 = r8
   esp = EXPONENT(r4)
   dig = DIGITS(r4)
   rad = RADIX(r4)
   print*," RRSPACING(",r4,") = ",RRSPACING(r4), &
          abs(r4*(rad**(-esp)))*rad**dig
   print*," SPACING(",r4,") = ",SPACING(r4), &
          rad**(esp-dig)
   end do
end program test_spacing