is_nan
An elegant way to return random float between two numbers:
<?php
function random_float ($min,$max) {
return ($min+lcg_value()*(abs($max-$min)));
}
?>
lcg_value
(PHP 4, PHP 5)
lcg_value — 组合线性同余发生器
说明
float lcg_value
( void
)
lcg_value() 返回范围为 (0, 1) 的一个伪随机数。本函数组合了周期为 2^31 - 85 和 2^31 - 249 的两个同余发生器。本函数的周期等于这两个素数的乘积。
返回值
范围为 (0, 1) 的伪随机数。
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User Contributed Notes
lcg_value - [3 notes]
rok kralj gmail com ¶
5 years ago
daniel dot baulig at gmx dot de ¶
3 years ago
Choose your weapon:
<?php
function mt_randf($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 ¶
5 years ago
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.