;;; 4.11a.scm
;;; 2016-03-26, 2024-09-15
;;; $Id: 4.11a.scm 1.2 2024/11/02 07:43:49 s Exp $

(define (main args)
  ; x  : cash flow stream
  ; s  : spot rate
  ; d  : discount factor
  ; pv : present value

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

  ; input
  (define x          '(-40 10  10  10  10  10  10 ))
  (define s_percent  '(  0 5.0 5.3 5.6 5.8 6.0 6.1))

  ; calculate
  (define k  (iota (length x)))
  (define s  (map  (lambda (x)   (/ x 100))        s_percent))
  (define d  (map  (lambda (x i) (/ 1 (expt (+ 1 x) i))) s k))
  (define xd (map  * x d ))
  (define pv (sum  xd))

  ; output
  (print "4.11a.scm")
  (print "k " (map (lambda (x) (format "~6d"   x)) k ))
  (print "s " (map (lambda (x) (format "~6,3f" x)) s ))
  (print "d " (map (lambda (x) (format "~6,3f" x)) d ))
  (print "x " (map (lambda (x) (format "~6d"   x)) x ))
  (print "xd" (map (lambda (x) (format "~6,2f" x)) xd))
  (print "pv"                  (format "~7,2f" pv))
0)
;;; end