Fibs in your favourite language

fibs = 1 : zipWith (+) fibs (tail fibs)

Not this shit again.

fibs = [ 1,1,2.. ]

I think we have enough fibs and fact threads.

fibs and fact are all that most /prog/ regulars are capable of


int fibs[] = {0,1,1,2,3,5,8,13,21,34,55,89,144,233,377,610,987,1597,2584,4181,6765};

int fib(int n){
    if(n<0 || n>20) exit();
    return fibs[n];
}

Compile with -O3.

>>6
lmao

F# fibonacci, using sequences

let fibs = (1I, 1I) |> Seq.unfold (fun (a,b) -> Some (a, (b,a+b)))

What it does:
The bigint tuple (1I, 1I) is piped into the Seq.unfold function. Seq.unfold takes a function and a seed (the 2-tuple in this case.) The function you pass in should take in as an argument the same type as the seed, so it's the tuple (a,b) as above.
The function returns a 2-tuple option value. An option value is simple None or an actual value. Returning None at any stage will termiante the sequence.
The first value in the returned tuple is the value you want to yield in the sequence. The second value in the tuple is the new accumulator, to be passed into the function on the next iteration of the sequence. In our case, it will be the next iteration of fibonacci, (b, a+b).
F# sequences, obviously, are lazy evaluated. To access the nth value of the sequence, simply use
let nthfib = fibs |> Seq.nth n

My fibs and fact defined in my personal language:

fibs = 0 + 1 + (.. + .)
fact = n * (. * [n - 1 != 0])

. and .. are defined as the previous arguments to the function.

>>8
fuck off F# user

>>10
I've been really getting into F# lately, especially since Microsoft have decided to include it as an official .NET language in the next Visual Studio iteration.

Check out the wikibook at
http://en.wikibooks.org/wiki/Programming:F_Sharp

Also my user page at
http://en.wikibooks.org/wiki/User:Awesome_Princess

>>11
You're cute :3

Exercise 2: Define fact in terms of fibs.

>>13
fact n = (n*fibs(1))*(fact n-1)

>> ಠ_ಠ

GOD DAMN IT HASKELL BE USEFUL FOR ONCE

>>16
Haskell can be used for making super fast fibonacci functions (Thanks dons!) It can also be used to parallelize fibonacci functions!

Honestly, what more do you need? IO? Input from the outside world is PIG DISGUSTING. Your programs are not pure.

>>16
One word Xmonad thread over

>>18
Awesome can do the same thing without requiring a 380 mb Haskell compiler.

>>19
What's the matter, don't want to actually use the 320GB h.disc?

Nobody seems to have pointed out that >>1 doesn't work.

>>16
How can you expect something so lazy to be useful?

>>19
Anonix developer detected

sbif([1,0]).
sbif([A,B,C|Rest]) :- sbif([B,C|Rest]), A is B + C.

fibs(Fibs) :- sbif(Sbif), reverse(Sbif, Fibs).

>>21
WHY

>>18
>>19
I also use XMonad. It is made of win and good. It's also stable, and has never crashed for me, unlike Awesome.

#include <math.h>

#define SQRT5 sqrtl(5)
#define PI (atanl(1) * 4)
#define FIB(n) ((1 / SQRT5) * (powl((SQRT5 + 1) / 2, n) - powl(2 / (SQRT5 + 1), n) * cosl(n * PI)))

>>27
Enjoy you're loss of precision.

(define (fib n)
  (define (iter a b p q count)
    (cond ((= count 0) b)
          ((even? count)
           (iter a
                 b
                 (+ (* p p) (* q q))
                 (+ (* 2 p q) (* q q))
                 (/ count 2)))
          (else (iter (+ (* b q) (* a q) (* a p))
                      (+ (* b p) (* a q))
                      p
                      q
                      (- count 1)))))
  (iter 1 0 0 1 n))

>>28
enjoy your slow as fuck.

(def fibs (lazy-cat [1 1] (map + fibs (rest fibs))))
user=> (time (nth fibs 40))
"Elapsed time: 0.05548 msecs"
165580141

Copy/Paste Clojure

>>29
Excuse me?  This is an optimal algorithm, handed down from Der Süßmann himself.

(time (nth fibs 10000))
"Elapsed time: 166.846 msecs"
54438373113565281338734260993750380135389184554695967026247715841208582865622349017083051547938960541173822675978026317384359584751116241439174702642959169925586334117906063048089793531476108466259072759367899150677960088306597966641965824937721800381441158841042480997984696487375337180028163763317781927941101369262750979509800713596718023814710669912644214775254478587674568963808002962265133111359929762726679441400101575800043510777465935805362502461707918059226414679005690752321895868142367849593880756423483754386342639635970733756260098962462668746112041739819404875062443709868654315626847186195620146126642232711815040367018825205314845875817193533529827837800351902529239517836689467661917953884712441028463935449484614450778762529520961887597272889220768537396475869543159172434537193611263743926337313005896167248051737986306368115003088396749587102619524631352447499505204198305187168321623283859794627245919771454628218399695789223798912199431775469705216131081096559950638297261253848242007897109054754028438149611930465061866170122983288964352733750792786069444761853525144421077928045979904561298129423809156055033032338919609162236698759922782923191896688017718575555520994653320128446502371153715141749290913104897203455577507196645425232862022019506091483585223882711016708433051169942115775151255510251655931888164048344129557038825477521111577395780115868397072602565614824956460538700280331311861485399805397031555727529693399586079850381581446276433858828529535803424850845426446471681531001533180479567436396815653326152509571127480411928196022148849148284389124178520174507305538928717857923509417743383331506898239354421988805429332440371194867215543576548565499134519271098919802665184564927827827212957649240235507595558205647569365394873317659000206373126570643509709482649710038733517477713403319028105575667931789470024118803094604034362953471997461392274791549730356412633074230824051999996101549784667340458326852960388301120765629245998136251652347093963049734046445106365304163630823669242257761468288461791843224793434406079917883360676846711185597501

Wow you can't do that in C.

>>31
He was using it to demonstrate linear growth.

With SICP is the Instructor's Manual.

You need both.

>>30
hotaru@olorin$ cat test.c                                                 < ~ >
#include <stdio.h>
#include "fib.c"

int main(void){
 for(int i = 0; i < 1000; ++i) printf("%Lf\n", FIB(i));
 return 0;
}
hotaru@olorin$ gcc -std=c99 -O2 -s -lm test.c                             < ~ >
hotaru@olorin$ time ./a.out > /dev/null                                   < ~ >
./a.out > /dev/null  0,08s user 0,01s system 96% cpu 0,095 total

fib←{⎕ml←3
        ⍵≤2:1

        {(+/^\⍵='0')↓⍵
        },'ZI9'⎕fmt(⍵-2){
            ⍺>0:(⍺-1)∇(↑⌽⍵)({
                ^/⍵<1e9:⍵ ⋄ (1e9|⍵)+1⌽⍵≥1e9
            }(↑⍵)+↑⌽⍵) ⋄ ↑⌽⍵
        }2⍴⊂(-⌈⍵÷40)↑1
    }

>>32
hotaru@olorin$ cat test.c                                                 < ~ >
#include <stdio.h>
#include <gmp.h>

int main(void){
 mpz_t n;
 mpz_init(n);
 mpz_fib_ui(n, 10001);
 mpz_out_str(stdout, 10, n);
 putchar('\n');
 return 0;
}
hotaru@olorin$ gcc -std=c99 -O2 -s -lgmp test.c                           < ~ >
hotaru@olorin$ time ./a.out                                               < ~ >
54438373113565281338734260993750380135389184554695967026247715841208582865622349017083051547938960541173822675978026317384359584751116241439174702642959169925586334117906063048089793531476108466259072759367899150677960088306597966641965824937721800381441158841042480997984696487375337180028163763317781927941101369262750979509800713596718023814710669912644214775254478587674568963808002962265133111359929762726679441400101575800043510777465935805362502461707918059226414679005690752321895868142367849593880756423483754386342639635970733756260098962462668746112041739819404875062443709868654315626847186195620146126642232711815040367018825205314845875817193533529827837800351902529239517836689467661917953884712441028463935449484614450778762529520961887597272889220768537396475869543159172434537193611263743926337313005896167248051737986306368115003088396749587102619524631352447499505204198305187168321623283859794627245919771454628218399695789223798912199431775469705216131081096559950638297261253848242007897109054754028438149611930465061866170122983288964352733750792786069444761853525144421077928045979904561298129423809156055033032338919609162236698759922782923191896688017718575555520994653320128446502371153715141749290913104897203455577507196645425232862022019506091483585223882711016708433051169942115775151255510251655931888164048344129557038825477521111577395780115868397072602565614824956460538700280331311861485399805397031555727529693399586079850381581446276433858828529535803424850845426446471681531001533180479567436396815653326152509571127480411928196022148849148284389124178520174507305538928717857923509417743383331506898239354421988805429332440371194867215543576548565499134519271098919802665184564927827827212957649240235507595558205647569365394873317659000206373126570643509709482649710038733517477713403319028105575667931789470024118803094604034362953471997461392274791549730356412633074230824051999996101549784667340458326852960388301120765629245998136251652347093963049734046445106365304163630823669242257761468288461791843224793434406079917883360676846711185597501
./a.out  0,01s user 0,00s system 76% cpu 0,009 total

>>36
http://forums.xkcd.com/viewtopic.php?f=40&p=1172786

Have you read your XKCD today?

>>33
What linear growth?

>>35
It carries out and is ⍵.

>>37
i cried while reading those posts