PHP 7.0.6 Released

stats_cdf_poisson

(PECL stats >= 1.0.0)

stats_cdf_poissonCalculates any one parameter of the Poisson distribution given values for the others.

Description

float stats_cdf_poisson ( float $par1 , float $par2 , int $which )
Warning

This function is currently not documented; only its argument list is available.

Parameters

par1

par2

which

Return Values

User Contributed Notes

s at nder dot com
3 years ago
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";

?>
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