suzanne.soy/scribble-math
1
0
Fork 0
Code Issues 8 Pull Requests 3 Actions Packages Projects Releases Wiki Activity

Added Match-linear-form. Checks if u has the form ax+b. Tests included.

Browse Source
This commit is contained in:
Jens Axel Søgaard 2012-07-04 21:55:13 +02:00
parent b99935f357
commit 44046df111
1 changed files with 32 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

44
bracket/bracket.rkt
View File

@ -1192,33 +1192,38 @@
)
#;(module pattern-matching racket
(module pattern-matching racket
(require (submod ".." expression)
(submod ".." bracket))
(define (linear-form u x)
; u expression, x a symbol
(provide Match-linear-form)
(define (Match-linear-form u x)
; INPUT u expression, x a symbol
; Checks if u has the form ax+b.
; If so List(a,b) is returned, otherwise #f
(if (eq? u x)
(list 1 0)
(List 1 0)
(case (kind u)
[(symbol-id integer fraction real complex)
(list 0 u)]
(List 0 u)]
[(Times)
(if (free-of u x)
(list 0 u)
(List 0 u)
(let ([u/x (Quotient u x)])
(if (Free-of u/x x)
(list u/x 0)
(List u/x 0)
#f)))]
[(Plus)
(let ([f (linear-form (operand u 1) x)])
(let ([f (Match-linear-form (operand u 1) x)])
(and f
(let ([r (linear-form (Minus u (operand u 1)))])
(let ([r (Match-linear-form (Minus u (operand u 1)) x)])
(and r
(list (+ (operand f 0) (operand r 0))
(+ (operand f 1) (operand r 1)))))))]
(List (Plus (operand f 0) (operand r 0))
(Plus (operand f 1) (operand r 1)))))))]
[else
(and (free-of u x)
(list 0 u))]))))
(List 0 u))]))))
(module test racket
(require (submod ".." symbolic-application)
@ -1374,6 +1379,21 @@
(check-equal? (Range x) '(Range x))
(check-equal? (Range x y) '(Range x y))
(check-equal? (Range x y z) '(Range x y z))
;;; Pattern Matching
; Match-linear-form
(require (submod ".." pattern-matching))
(check-equal? (Match-linear-form 42 x) (List 0 42))
(check-equal? (Match-linear-form (Times 42 x) x) (List 42 0))
(check-equal? (Match-linear-form (Times 42 x) y) (List 0 (Times 42 x)))
(check-equal? (Match-linear-form x x) (List 1 0))
(check-equal? (Match-linear-form (Sin x) x) #f)
(check-equal? (Match-linear-form (Plus 2 (Sin x)) x) #f)
(check-equal? (Match-linear-form (Power x 2) x) #f)
(check-equal? (Match-linear-form (Times 3 x x y) x) #f)
(check-equal? (Match-linear-form (Plus 3 (Power x 2) y) x) #f)
(check-equal? (Match-linear-form (Plus 3 x y) x) (List 1 (Plus 3 y)))
)