On Monday, 11 May 2015 at 21:15:33 UTC, Dzhon Smit wrote:
Just in case you wonder, here's a comparison of the Fibonacci
numbers. The D code was written by Dennis Ritchie (a user of
this forum, not the guy who invented C).
[code]import std.stdio, std.bigint;
void main() {
BigInt[] fib1, fib2;
BigInt last = 0, next = 1;
int n = 100000;
int i;
while (i != n) {
fib1 ~= last, last = next, next += fib1[$ - 1];
++i;
}
i = 0, last = 0, next = 1;
while (i != n) {
fib2 ~= last, last = next, next += fib2[$ - 1];
++i;
}
BigInt sumFib1;
foreach (e; fib1) {
sumFib1 += e;
}
BigInt sumFib2;
foreach (e; fib2) {
sumFib2 += e;
}
writeln(sumFib2 - sumFib1); // 0
}[/code]
[code];;;; fib.lisp
(defun main ()
(let ((n 100000))
(let ((fib1 (do ((i 0 (incf i))
(last 0 next)
(next 1 (+ next last))
(fib '() (cons last fib)))
((= i n) (nreverse fib))))
(fib2 (do ((i 0 (incf i))
(last 0 next)
(next 1 (+ next last))
(fib '() (cons last fib)))
((= i n) (nreverse fib)))))
(let ((sum-fib-1 (loop :for e :in fib1 :sum e))
(sum-fib-2 (loop :for e :in fib2 :sum e)))
(- sum-fib-2 sum-fib-1)))))
(format t "~D~%" (main))[/code]
Tests on my machine:
[code]$ time ./fib
0
real 0m6.458s
user 0m2.250s
sys 0m0.933s
$ time sbcl --dynamic-space-size 4GB --script fib.lisp
0
real 0m1.884s
user 0m1.290s
sys 0m0.260s[/code]
It's some kind of stuffing the community Lisp programmers who try
to prove that SBSL faster than D. Nothing like that.
