! 3.7.f90
! $Id: 3.7.f90 1.1 2017/01/07 12:48:47 s Exp $
!
! a    : annual worth
! cf   : cash flow
! cfdf : cf x df
! df   : discount factor
! n    : number of periods
! pv   : present value
! r    : interest rate

implicit none

integer :: k, n
integer, dimension(0:10) :: i, i_a, i_b
double precision, dimension(0:10) :: a, cf, cfa,cfb, cfadf,cfbdf, cfdf, df
double precision :: a_a, a_b, pp, pv, pv_a_a, pv_a_b, r
character(100)   :: dash, fmt1, fmt2

! Car A

! input
dash='----------'
i(0:6)  = (/(k, k = 0, 6)/)
r = 0.1d0
n = 4
cf(0:n) = (/20.0d3, 1.0d3, 1.0d3, 1.0d3, 0.0d0/)

! calculate
df(0:n) = 1.0d0 / (1.0d0 + r) ** i(0:n)
cfdf(0:n) = cf(0:n) * df(0:n)
pv = sum(cf(0:n) * df(0:n))
a_a  = r * (1 + r) ** n * (pv) / ((1 + r) ** n -1)
cfa(0:n) = (/0.0d0, a_a, a_a, a_a, a_a/)
cfadf(0:n) = cfa(0:n) * df(0:n)
pv_a_a = sum(cfadf(0:n))

! output
print *, 'Car A'
print '(a10,5i10)',   'n', n
print '(a10,5f10.3)', 'r', r
print '(a10,5i10)',   'k', i(0:n)
print '(60a10)', dash,dash,dash,dash,dash,dash
print '(a10,5f10.3)', 'cf', cf(0:n)
print '(a10,5f10.3)', 'df', df(0:n)
print '(a10,5f10.3)', 'cfdf', cfdf(0:n)
print '(60a10)', dash,dash,dash,dash,dash,dash
print '(a10,5f10.3)', 'pv', pv
print *,
print '(a20,5f10.3)', 'annual worth', a_a
print *,
print *, 'verification of accounts'
print '(60a10)', dash,dash,dash,dash,dash,dash
print '(a10,5f10.3)', 'cf', cfa(0:n)
print '(a10,5f10.3)', 'df', df(0:n)
print '(a10,5f10.3)', 'cfdf', cfadf(0:n)
print '(60a10)', dash,dash,dash,dash,dash,dash
print '(a10,5f10.3)', 'pv', pv_a_a

! Car B

! input
n = 6
cf(0:n) = (/30.0d3, 2.0d3, 2.0d3, 2.0d3, 2.0d3, 2.0d3, 0.0d0/)

! calculate
df(0:n) = 1.0d0 / (1.0d0 + r) ** i(0:n)
cfdf(0:n) = cf(0:n) * df(0:n)
pv = sum(cf(0:n) * df(0:n))
a_b  = r * (1 + r) ** n * (pv) / ((1 + r) ** n -1)
cfb(0:n) = (/0.0d0, a_b, a_b, a_b, a_b, a_b, a_b/)
cfbdf(0:n) = cfb(0:n) * df(0:n)
pv_a_b = sum(cfbdf(0:n))

! output
print *,
print *, 'Car B'
print '(a5,7i10)',   'n', n
print '(a5,7f10.3)', 'r', r
print '(a5,7i10)',   'k', i(0:n)
print '(7a10,a5)', dash,dash,dash,dash,dash,dash,dash,'-----'
print '(a5,7f10.3)', 'cf', cf(0:n)
print '(a5,7f10.3)', 'df', df(0:n)
print '(a5,7f10.3)', 'cfdf', cfdf(0:n)
print '(7a10,a5)', dash,dash,dash,dash,dash,dash,dash,'-----'
print '(a5,7f10.3)', 'pv', pv
print *,
print '(a20,7f10.3)', 'annual worth', a_b
print *,
print *, 'verification of accounts'
print '(7a10,a5)', dash,dash,dash,dash,dash,dash,dash,'-----'
print '(a5,7f10.3)', 'cf', cfb(0:n)
print '(a5,7f10.3)', 'df', df(0:n)
print '(a5,7f10.3)', 'cfdf', cfbdf(0:n)
print '(7a10,a5)', dash,dash,dash,dash,dash,dash,dash,'-----'
print '(a5,7f10.3)', 'pv', pv_a_b

stop
end