如何在php中将pi计算为设定的位数? [英] How can pi be calculated to a set number of digits in PHP?

问题描述

如何计算PHP中pi的值(最多X个十进制数字).

How can I calculate the value of pi in PHP up to X decimal numbers.

4个小数点

3.141

3.141

64个小数点

3.141592653589793238462643383279502884197169399375105820974944592

3.141592653589793238462643383279502884197169399375105820974944592

推荐答案

找到了@Konamiman发布的断开链接的来源.

Found the source for the broken link @Konamiman posted.

将结果与以下内容进行比较: http://www.angio.net/pi/digits /50.txt 和它们相同.

Compared the results to: http://www.angio.net/pi/digits/50.txt and they are the same.

// Source: http://mgccl.com/2007/01/22/php-calculate-pi-revisited
function bcfact($n)
{
    return ($n == 0 || $n== 1) ? 1 : bcmul($n,bcfact($n-1));
}
function bcpi($precision)
{
    $num = 0;$k = 0;
    bcscale($precision+3);
    $limit = ($precision+3)/14;
    while($k < $limit)
    {
        $num = bcadd($num, bcdiv(bcmul(bcadd('13591409',bcmul('545140134', $k)),bcmul(bcpow(-1, $k), bcfact(6*$k))),bcmul(bcmul(bcpow('640320',3*$k+1),bcsqrt('640320')), bcmul(bcfact(3*$k), bcpow(bcfact($k),3)))));
        ++$k;
    }
    return bcdiv(1,(bcmul(12,($num))),$precision);
}

echo bcpi(1000);

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