#include <stdio.h>
#include <math.h>
 
typedef unsigned int Uint;
#define N 1000
Uint DP=1;
//RADIX == 10^LOG
#define LOG 1
#define RADIX 10
typedef Uint Liczba[N+1];
 
void pisz( Liczba a, int ctrl){ Uint i;
	for( i=1; i<DP && !a[i]; i++ ) printf("%*s", LOG,"");
	printf("%*u", LOG, a[i]);
	for( i++; i<=DP; i++ ) printf("%0*u", LOG, a[i]);
	putchar('.');
	for(    ; i<=N; i++ ) printf("%0*u", LOG, a[i]); 
	if( ctrl < 0 ) puts("");}
 
void plus( Liczba a, Liczba b){                  // a[]:=a[]+b[]
	for( Uint c=0, i=N; i>0; i-- ){
		c += a[i]+b[i];
		a[i] = c % RADIX;
		c /= RADIX;}}
 
void minus( Liczba a, Liczba b ) {               // a[]:=a[]-b[]
	for( Uint c=0, i=N; i>0; i-- ){
		c += b[i];
		if( a[i]<c ){
			a[i] = RADIX + a[i] - c; c=1; }
		else {
			a[i] -= c; c=0; }}}
 
void razyU( Liczba a, Uint b ) {                 // a[]:=a[] * b
	for( Uint c=0,i=N; i>0; i-- ){
		c += a[i]*b;
		a[i]= c % RADIX;
		c /= RADIX; }}
 
int podzielU( Liczba w, Liczba a, Uint b ) {     // w[]:=a[] / b
	Uint z=0;                                // return w[] != 0
	for( Uint c=0, i=1; i<=N; i++ ) {
		c = c*RADIX+a[i];
		w[i]= c/b % RADIX; if( w[i] ) z=1;
		c = c - w[i]*b;}
	return z;}
 
void wstawU( Liczba a, Uint b ) {                // a[]:= b
	Uint i;
	for( i=0; i<=N; i++ ) a[i]=0;
	i=DP;
	while( b ) {
		a[i--] = b%RADIX; b /= RADIX; }}
 
void atg( Liczba a, Uint x ) {                  // a[]:= atan( 1/x )
	Liczba px;
	wstawU( px, 1 ); podzielU( px, px, x );
	wstawU( a,  0 ); plus    ( a, px );
	for( Uint n=1;   ; n++){
		Liczba b;
		podzielU( px, px, x*x );
		if( ! podzielU( b, px, 2*n + 1 ) )
			break;
		if( n & 1 ) minus( a, b );
		else plus( a, b );}}	            
 
int main(void) {
	Liczba a1, a2;
	atg( a1, 5 ); 	razyU( a1, 4 );
	atg( a2, 239);
	minus( a1, a2 );
	razyU( a1, 4 );
	pisz( a1, -1 ); 
	puts(	"3,141592653589793238462643383279502884197169399375"
		"10582097494459230781640628620899862803482534211706"
		"79821480865132823066470938446095505822317253594081"
		"28481117450284102701938521105559644622948954930381");
	return 0;
}
 

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