pidigits.php-3.php

<?php 
/* The Great Computer Language Shootout
   http://shootout.alioth.debian.org/

   contributed by Oleksii Prudkyi
   port from pidigits.lua-5.lua (Mike Pall, Wim Couwenberg)
*/

$N = (int) $argv[1];
ob_start(null, 1);

$w = gmp_init(0);

$k = 1;
$n1 = gmp_init(4);
$n2 = gmp_init(3);
$d = gmp_init(1);

$i = 0;
while(true) {
	//digit
	$u = gmp_div_q($n1, $d);
	$v = gmp_div_q($n2, $d);
	if(gmp_cmp($u, $v) == 0) {
		echo gmp_strval($u);
		++$i;
		if($i % 10 == 0) {
			echo "\t:" , $i , "\n";
		}
		if($i == $N) {
			break;
		}
		//extract
		$u = gmp_mul($d, gmp_mul(-10, $u));
		$n1 = gmp_mul($n1, 10);
		$n1 = gmp_add($n1, $u);
		$n2 = gmp_mul($n2, 10);
		$n2 = gmp_add($n2, $u);
	} else {
		//produce
		$k2 = $k << 1;
		$u = gmp_mul($n1, $k2 - 1);
		$v = gmp_add($n2, $n2);
		$w = gmp_mul($n1, $k - 1);
		$n1 = gmp_add($u, $v);
		$u = gmp_mul($n2, $k + 2);
		$n2 = gmp_add($w, $u);
		$d = gmp_mul($d, $k2 + 1);
		++$k;
	}
}
if($i % 10 != 0) {
	echo str_repeat(' ', 10 - $N % 10), "\t:", $N, "\n";
}

ob_end_flush();