<?php
//bcpi function with Gauss-Legendre algorithm
//by Chao Xu (Mgccl)
function bcpi($precision)
{
$limit = ceil(log($precision) / log(2)) - 1;
bcscale($precision + 6);
$a = 1;
$b = bcdiv(1, bcsqrt(2));
$t = 1 / 4;
$p = 1;
$n = 0;
while ($n < $limit) {
$x = bcdiv(bcadd($a, $b), 2);
$y = bcsqrt(bcmul($a, $b));
$t = bcsub($t, bcmul($p, bcpow(bcsub($a, $x), 2)));
$a = $x;
$b = $y;
$p = bcmul(2, $p);
++$n;
}
return bcdiv(bcpow(bcadd($a, $b), 2), bcmul(4, $t), $precision);
}
echo bcpi($_GET['precision']);
return bcdiv(bcpow(bcadd($a, $b), 2), bcmul(4, $t), $precision);
}
?>
<html>
<head>
<script>
</script>
</head>
<body>
<div><?php
echo date(DATE_RFC822) . " at " . gethostname();
?>
</div>
<div>Calculating pi to a precision of <?php
echo $precision;
?>
</div>
<div style="width: 700px; word-wrap:break-word;">
<?php
flush();
echo bcpi($precision);
?>
</div>
</body>
</html>
