# 2.6.jl
# 2020-11-23, 2025-6-28
# $Id: 2.6.jl 1.2 2025/06/28 07:49:12 s Exp $

# function
pv = (x, r, k) -> x / (1 + r) ^ k # present value

# input
r = 0.12 # rate
i1   = [    0,     1,     2,     3,     4,     5] # index stream
cfs1 = [-1000, -1000, -1000, -1000, -1000, -1000] # cash flow sream
i2   = [    0,     1,     2,     3,     4,     5]
cfs2 = [ -900,  -900,  -900,  -900,  -900,  -900]
cfs2[1] += -1000
i3  =[    0,    1,     2,   3,    4,    5,    6,    7,    8,    9,   10,   11]
cfs3=[-1000,-1000,-1000,-1000,-1000,-1000,-1000,-1000,-1000,-1000,-1000,-1000]
i4  =[    0,    1,     2,   3,    4,    5,    6,    7,    8,    9,   10,   11]
cfs4=[ -900, -900, -900, -900, -900, -900, -900, -900, -900, -900, -900, -900]
cfs4[1] += -1000

# calcuration 
pv1 = sum(map((x,k) -> pv(x, r, k), cfs1, i1))
pv2 = sum(map((x,k) -> pv(x, r, k), cfs2, i2))
pv3 = sum(map((x,k) -> pv(x, r, k), cfs3, i3))
pv4 = sum(map((x,k) -> pv(x, r, k), cfs4, i4))

# output
println("2.6.jl")
println("r= $r")
println("cfs1 $cfs1")
println("cfs2 $cfs2")
println("cfs3 $cfs3")
println("cfs4 $cfs4")
println("pv1= $(round(Int, pv1))")
println("pv2= $(round(Int, pv2))")
println("pv3= $(round(Int, pv3))")
println("pv4= $(round(Int, pv4))")
# eof