46 lines
1.3 KiB
Scheme
46 lines
1.3 KiB
Scheme
|
;;; DERIV -- Symbolic derivation.
|
||
|
|
|
||
|
|
;;; Returns the wrong answer for quotients.
|
||
|
|
;;; Fortunately these aren't used in the benchmark.
|
||
|
|
|
||
|
|
(define (deriv a)
|
||
|
|
(cond ((not (pair? a))
|
||
|
|
(if (eq? a 'x) 1 0))
|
||
|
|
((eq? (car a) '+)
|
||
|
|
(cons '+
|
||
|
|
(map deriv (cdr a))))
|
||
|
|
((eq? (car a) '-)
|
||
|
|
(cons '-
|
||
|
|
(map deriv (cdr a))))
|
||
|
|
((eq? (car a) '*)
|
||
|
|
(list '*
|
||
|
|
a
|
||
|
|
(cons '+
|
||
|
|
(map (lambda (a) (list '/ (deriv a) a)) (cdr a)))))
|
||
|
|
((eq? (car a) '/)
|
||
|
|
(list '-
|
||
|
|
(list '/
|
||
|
|
(deriv (cadr a))
|
||
|
|
(caddr a))
|
||
|
|
(list '/
|
||
|
|
(cadr a)
|
||
|
|
(list '*
|
||
|
|
(caddr a)
|
||
|
|
(caddr a)
|
||
|
|
(deriv (caddr a))))))
|
||
|
|
(else
|
||
|
|
(fatal-error "No derivation method available"))))
|
||
|
|
|
||
|
|
(define (main . args)
|
||
|
|
(run-benchmark
|
||
|
|
"deriv"
|
||
|
|
deriv-iters
|
||
|
|
(lambda (result)
|
||
|
|
(equal? result
|
||
|
|
'(+ (* (* 3 x x) (+ (/ 0 3) (/ 1 x) (/ 1 x)))
|
||
|
|
(* (* a x x) (+ (/ 0 a) (/ 1 x) (/ 1 x)))
|
||
|
|
(* (* b x) (+ (/ 0 b) (/ 1 x)))
|
||
|
|
0)))
|
||
|
|
(lambda (a) (lambda () (deriv a)))
|
||
|
|
'(+ (* 3 x x) (* a x x) (* b x) 5)))
|