<? $start_time = microtime(true); $n=5000; // 圆周率的长度 $w = $n+10; $b =bcpow(10,$w); $rtemp=bcmul($left=$b, $right=4); $x1 =bcdiv($left=$rtemp, $right=5); $x2 =bcdiv($left=$b, $right=-239); $he=bcadd($left=$x1, $right=$x2); $n =$n*2; for ($i=3; $i<$n; $i =…