Pi-calculator

Gepost door manu hobert op 05-09-2010 17:29.

Mijn script om pi te berekenen

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<?php
$start_time = microtime(true);

$digits = 100; //hoeveel digits je wilt
bcscale($digits+10); //+10 for the extra precision

$output_pi = "3.";
$pi = 0;
$k = 0;
    //calculate first iteration
        $a = bcdiv(1, bcpow(16,$k));
        $b = bcdiv(4, (8*$k+1));
        $c = bcdiv(2, (8*$k+4));
        $d = bcdiv(1, (8*$k+5));
        $e = bcdiv(1, (8*$k+6));
            $f = bcsub($b, $c);
            $g = bcsub($f, $d);
            $h = bcsub($g, $e);
                $i = bcmul($a, $h);
                    $pi = bcadd($pi, $i);

for($k = 1;$k <= $digits;$k++){
    set_time_limit(60);
    //calculate next iteration
    
        $a = bcdiv(1, bcpow(16,$k));
        $b = bcdiv(4, (8*$k+1));
        $c = bcdiv(2, (8*$k+4));
        $d = bcdiv(1, (8*$k+5));
        $e = bcdiv(1, (8*$k+6));
            $f = bcsub($b, $c);
            $g = bcsub($f, $d);
            $h = bcsub($g, $e);
                $i = bcmul($a, $h);
                    $pi = bcadd($pi, $i);
}
echo bcadd($pi, 0, $digits);
echo "<br>";
$time = microtime(true) - $start_time;
echo "we have calculated " . $digits . " digits in " . $time . " seconds !";
?>

wat het doet
-het berekend pi met ... getallen na de komma
-het is snel ≈ 5seconden voor 1000 getallen
-het zegt hoelang het erover gedaan heeft

Bestanden van dit script

pi.php

pi.php

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<?php
$start_time = microtime(true);

$digits = 100; //hoeveel digits je wilt
bcscale($digits+10); //+10 for the extra precision

$output_pi = "3.";
$pi = 0;
$k = 0;
    //calculate first iteration
        $a = bcdiv(1, bcpow(16,$k));
        $b = bcdiv(4, (8*$k+1));
        $c = bcdiv(2, (8*$k+4));
        $d = bcdiv(1, (8*$k+5));
        $e = bcdiv(1, (8*$k+6));
            $f = bcsub($b, $c);
            $g = bcsub($f, $d);
            $h = bcsub($g, $e);
                $i = bcmul($a, $h);
                    $pi = bcadd($pi, $i);

for($k = 1;$k <= $digits;$k++){
    set_time_limit(60);
    //calculate next iteration
    
        $a = bcdiv(1, bcpow(16,$k));
        $b = bcdiv(4, (8*$k+1));
        $c = bcdiv(2, (8*$k+4));
        $d = bcdiv(1, (8*$k+5));
        $e = bcdiv(1, (8*$k+6));
            $f = bcsub($b, $c);
            $g = bcsub($f, $d);
            $h = bcsub($g, $e);
                $i = bcmul($a, $h);
                    $pi = bcadd($pi, $i);
}
echo bcadd($pi, 0, $digits);
echo "<br>";
$time = microtime(true) - $start_time;
echo "we have calculated " . $digits . " digits in " . $time . " seconds !";
?>