#lang racket
(require string-util)

(define (acc x n)
  (* (string->number x) (expt 2 n))
  )
 

(define (n_div x y)
  (round (/ x y))
)

(define (log2 x)
  (define (rec x y)
    (if (< x 1)
        ;then
        y
        ;else
        (rec (quotient (floor x) 2) (+ y 1))
    )
  )
  (rec (- x 1) 0)
)

(define (rround num prec)
  (string->number (real->decimal-string num prec))
  )


(define (rmul x y n)
  (define (sub_mul)
    (define k (+ q r 1))
    (define l (+ p s 1))
    (define m (+ p q n 4))
    (rround (/ (* (acc y l) (acc x k)) (expt 2 m)) n)
   )
  
  (define n2 (+ n 2))
  (define r (quotient n2 2))
  (writeln r)
  (define s (- n2 r))
  (writeln s)
  (define xr (acc x r))
  (define ys (acc y s))
  (define p (log2 xr))
  (writeln p)
  (define q (log2 ys))
  (writeln q)
  (if (and (equal? p 0) (equal? q 0))
      ;then
      0
      ;else
      (sub_mul)
  )
)

(rmul "1.0003" "1.0002" 3)
;(el "35.34" 3)
;(acc "4.5" 3)