! 2.10b1.f90
! $Id: 2.10b1.f90 1.2 2019/09/16 00:11:43 s Exp $
!
program ex2_10b1
implicit none

! x[i]   : cash flow(i-th year)
! r      : interest rate
! df[i]  : discount factor(i-th year)
! pv[i]  : present value(i-th year)
! sumpv  : present value

  character(100) :: fmt1, fmt2, fmt3
  integer :: n, i
  integer :: j(0:100)
  real(8) :: r, sumpv
  real(8) :: df(0:100), pv(0:100), x(0:100)

! input
  r = 0.2
  n = 5
  x(0:n) = (/-1000d3, 840d3, 707500d0, 387500d0, 177500d0, 50d3/)
  j(0:n) = (/0, 1, 2, 3, 4, 5/)

! calculate
  df(0:n) = 1 / (1 + r) ** j(0:n)
  pv(0:n) = x(0:n) * df(0:n)
  sumpv = sum(pv(0:n))

! output
  fmt1 = '(a10, a10, a15,   a15)'
  fmt2 = '(i10, i10, f15.3, i15)'
  fmt3 = '(a35, i15)'
  print *, '2.10b1.f90'
  print fmt1, 'i', 'x', '1/(1+r)^i', 'x/(1+r)^i'
  call keisen(50)
  print fmt2, (i, nint(x(i)), df(i), nint(pv(i)), i = 0, n)
  call  keisen(50)
  print fmt3, 'present value=', nint(sumpv)
  stop

  contains
  subroutine keisen(n)
    implicit none
    integer :: i,n
    print *, ('-', i = 1, n)
  end subroutine keisen

end program ex2_10b1
! end