racket:
Welcome to Racket v5.2.1.
> (define (cycle-length n)
(cond
[(= n 1)
1]
[(odd? n)
(add1 (cycle-length (add1 (* 3 n))))]
[(even? n)
(add1 (cycle-length (/ n 2)))]))
(time (for ([i (in-range 1 1000000)])
(cycle-length i)))
>
cpu time: 15016 real time: 15018 gc time: 0
sbcl:
(defun cycle-length(n)
(cond ((= n 1) 1)
((oddp n) (1+ (cycle-length (1+ (* 3 n)))))
((evenp n) (1+ (cycle-length (/ n 2))))))
* (time (loop for i from 1 to 1000000 do (cycle-length i)))
Evaluation took:
6.192 seconds of real time
6.192387 seconds of total run time (6.192387 user, 0.000000 system)
100.00% CPU
14,496,643,427 processor cycles
0 bytes consed
With optimizations:
(defun cycle-length(n)
(declare (fixnum n)
(ftype (function (fixnum) fixnum) cycle-length)
(optimize (speed 3) (safety 0) (compilation-speed 0)))
(cond ((= n 1) 1)
((oddp n) (the fixnum (1+ (cycle-length
(the fixnum (1+ (the fixnum (* 3 n))))))))
((evenp n) (cycle-length (the fixnum (/ n 2))))))
CL-USER> (time (loop for i from 1 to (expt 10 6) do (cycle-length i)))
Evaluation took:
3.515 seconds of real time
3.524220 seconds of total run time (3.524220 user, 0.000000 system)
100.26% CPU
8,228,949,701 processor cycles
33,008 bytes consed
So racket = 15 seconds
sbcl = 6 seconds
sbcl optimized = 3.5 seconds.
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