pi 계산하기

http://www.iwriteiam.nl/SigProgC.html

Calculating Pi in 2 lines by Dik T. Winter

The following 160 character C program, written by Dik T. Winter at CWI, computes pi to 800 decimal digits.

#include<stdio.h>

int a=10000,b,c=2800,d,e,f[2801],g;main(){for(;b-c;)f[b++]=a/5;for(;d=0,g=c*2;c

-=14,printf("%.4d",e+d/a),e=d%a)for(b=c;d+=f[b]*a,f[b]=d%--g,d/=g--,--b;d*=b);}

He also wrote one for calculating the first 15,000 digits:

#include<stdio.h>

a[52514],b,c=52514,d,e,f=1e4,g,h;main(){for(;b=c-=14;h=printf("%04d",

e+d/f))for(e=d%=f;g=--b*2;d/=g)d=d*b+f*(h?a[b]:f/5),a[b]=d%--g;} 

For some background information, read Unbounded Spigot Algorithms for the Digits of Pi. (And even shorter.)