;;; 2.15a.scm
;;;
;;; $Id: 2.15a.scm 1.2 2024/10/27 09:12:29 s Exp $
;
; bc, Before-tax cash flow  : 税引き前キャッシュ・フロー
; da,  Depletion            : 減価償却 
; ti,  Taxable income       : 課税対象収益
; ta, tax                   : 税金
; ac, After-tax cash flow   : 税引き後キャッシュ・フロー
; tr, tax rate              : 税率
; ir, infration rate        : インフレ率
; ic, initial capital expenditure : 初期資本費用
; r,  discount rate         : 金利
; df, discount factor       : 割引係数(2011-10-29改)
; ny                        : 年数
; pv, present value of ac : 税引き後キャッシュ・フローの現在価値

(define (main args)
  ; procedure
  (define sum (lambda (x) (fold + 0 x)))

  ; input
  (define tr 0.34)
  (define ir 0.04)
  (define r  0.12)
  (define ic 10e6)
  (define ny 5)
  (define bc (list (- ic) 2990e3 2990e3 2990e3 2990e3 2990e3))
  (define da (list 0 (/ ic ny) (/ ic ny) (/ ic ny) (/ ic ny) (/ ic ny)))
  (define k  (iota (length bc)))

  ;calculating
  (define ti (map (lambda (x y) (if (> x y ) (- x y) 0)) bc da))
  (define ta (map (lambda (x)   (* x tr))    ti))
  (define ac (map (lambda (x y) (- x y )) bc ta))
  (define df (map (lambda (x)   (/ 1 (expt (+ 1 r) x))) k))
  (define pv (map (lambda (x y) (* x y)) ac df))
  (define sum_pv (sum pv))

  ; output
  (print "2.15a.scm")
  (print "k  " (map (lambda (x) (format "~9d"             x )) k ))
  (print "bc " (map (lambda (x) (format "~9d" (x->integer x))) bc))
  (print "da " (map (lambda (x) (format "~9d" (x->integer x))) da))
  (print "ti " (map (lambda (x) (format "~9d" (x->integer x))) ti))
  (print "ta " (map (lambda (x) (format "~9d" (x->integer x))) ta))
  (print "ac " (map (lambda (x) (format "~9d" (x->integer x))) ac))
  (print "df " (map (lambda (x) (format "~9,3f"           x )) df))
  (print "pv " (map (lambda (x) (format "~9d" (x->integer x))) pv))
  (print "sum of pv " (x->integer sum_pv))
0)
;;; end