Add extend-sylvester-radix operator.

sylvester-test.rkt

@@ -18,3 +18,11 @@
 
 (check-equal? (add-sylvester-radix '(0 1 2) '(1 1 2)) '(1 2 4))
 (check-equal? (add-sylvester-radix '(1) '(1)) '(0 1))
+
+(check-equal? ((extend-sylvester-radix 4) '()) '(0 0 0 0))
+(check-equal? ((extend-sylvester-radix 3) '(1 1)) '(1 1 0))
+(check-equal? ((extend-sylvester-radix 2) '(1 1)) '(1 1))
+(check-equal? ((extend-sylvester-radix 1) '(1 1)) '(1 1))
+
+
+

sylvester.rkt

@@ -41,12 +41,19 @@
  ;; 1337
  sylvester-radix-value
  
- ;; add two sylvester-radix numbers
+ ;; Add two sylvester-radix numbers
  ;;
  ;; Example:
  ;; > (add-sylvester-radix '(1 0 1) '(1 0 2))
  ;; '(0 1 3)
- add-sylvester-radix)
+ add-sylvester-radix
+
+ ;; Extend length of sylvester-radix number with zero elements.
+ ;;
+ ;; Example:
+ ;; > ((extend-sylvester-radix 4) '(1 2))
+ ;; '(1 2 0 0)
+ extend-sylvester-radix)
 
 ;; —————————————————————————————————
 ;; Implementation Section
@@ -73,6 +80,16 @@
 (define (add-sylvester-radix v w)
   (normalize-sylvester-radix (add-components v w)))
 
+;; Create procedure to extend list to length n
+(define (extend-sylvester-radix n)
+  (lambda (v)
+    (if (>= (length v) n)
+        v
+        (append v
+                (build-list
+                 (- n (length v))
+                 (lambda (x) 0))))))
+
 ;; Ensure digits are in the required range by carrying surplus value.
 (define (normalize-sylvester-radix v)
   (normalize-sylvester-helper v 0 0))