Умножение: Общий случай

Верхолин Игорь/README.md

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+# Умножение: общий случай
+## Ссылка на видеоразбор
+## Код из книги
+	let real_mul x y n =
+	let n2 = n + 2 in
+	let r = n2 / 2 in
+	let s = n2 − r in
+	let xr = x(r)
+	and ys = y (s) in
+	let p = log2 xr
+	and q = log 2 ys in
+	if p = 0 & q = 0 then Int 0 else
+	let k = q + r + 1
+	and l = p + s + 1
+	and m = p + q + 4 in
+	(x(k) ∗/ y(l)) ndiv ( Int 2 ∗∗/ Int m) ;;

Верхолин Игорь/mul.rkt

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+#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)
+
+