(PECL stats >= 1.0.0)
stats_cdf_poisson — Calculates any one parameter of the Poisson distribution given values for the others.
$par1
, float $par2
, int $which
)本函数还未编写文档，仅有参数列表。
par1
par2
which
s at nder dot com (2012-11-23 09:33:53)
A simple poisson-distribution function, which only works for relatively small numbers (maximum of ~100/100 for most systems):
<?php
function factorial($number)
{
if ($number < 2) {
return 1;
} else {
return ($number * factorial($number-1));
}
}
function poisson($chance, $occurrence)
{
$e = exp(1);
$a = pow($e, (-1 * $chance));
$b = pow($chance,$occurrence);
$c = factorial($occurrence);
return $a * $b / $c;
}
$test = poisson(100,100);
echo $test . "\n";
?>