Daniel-Nikpayuk_SICP-Solutions/Chapter 1/1.2/exercise-1.17/exercise.lsp
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;; Copyright 2015 Daniel Nikpayuk
;;
;; This file is part of SICP Solutions.
;;
;; SICP Solutions is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License
;; as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
;;
;; SICP Solutions is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty
;; of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
;;
;; You should have received a copy of the GNU General Public License along with SICP Solutions. If not, see
;; <http://www.gnu.org/licenses/>.
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;fast multiplication.

(define (halve x) (/ x 2))
(define (double x) (+ x x))

(define (fast-mult-r b n)
 (cond
  ((= n 0) 0)
  ((even? n) (double (fast-mult-r b (halve n))))
  (else (+ b (fast-mult-r b (- n 1))))
 )
)

