lcg_value

(PHP 4, PHP 5)

lcg_value — 複合線形合同法

説明

float lcg_value ( void )

lcg_value() は、(0, 1)の範囲の疑似乱数を返します。この関数は、周期が 2^31 - 85 および 2^31 - 249 の 2 つの CG を組み合わせます。この関数の周期はこれら 2 つの素数の積と等価です。

返り値

(0, 1) の範囲の疑似乱数を、浮動小数点数で返します。

参考

rand() - 乱数を生成する
mt_rand() - よりよい乱数値を生成する

log10

is_nan

[edit] Last updated: Fri, 25 May 2012

add a note User Contributed Notes lcg_value

daniel dot baulig at gmx dot de 03-Feb-2010 07:16


Choose your weapon:

<?php

function mt_randf($min, $max)

{

    return $min + abs($max - $min) * mt_rand(0, mt_getrandmax())/mt_getrandmax(); 

}

function lcg_randf($min, $max)

{

    return $min + lcg_value() * abs($max - $min);

}

function randf($min, $max)

{

    return $min + rand(0,getrandmax()) / getrandmax() * abs($max - $min);

}?>

jfdsmit at gmail dot com 17-Dec-2007 06:44


Be warned, the function provided by mr dot joebert at gmail dot com has a serious tendency to return $min more often than anything else, especially when $min and $max are close. It also will never return $max if $min is negative. rok kralj gmail com's implementation does not have this problem, as it operates on the difference between $max and $min instead of $max itself.

rok kralj gmail com 05-Jun-2007 08:54


An elegant way to return random float between two numbers:



<?php

function random_float ($min,$max) {

   return ($min+lcg_value()*(abs($max-$min)));

}

?>

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