stats_cdf_poisson

    (PECL stats >= 1.0.0)

    stats_cdf_poisson — Calculates any one parameter of the Poisson distribution given values for the others

    説明

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

    Returns the cumulative distribution function, its inverse, or one of its parameters, of the Poisson distribution. The kind of the return value and parameters (par1 and par2) are determined by which.

    The following table lists the return value and parameters by which. CDF, x, and lambda denotes cumulative distribution function, the value of the random variable, and the parameter of the Poisson distribution, respectively.

    Return value and parameters
    which Return value par1 par2
    1 CDF x lambda
    2 x CDF lambda
    3 lambda x CDF

    パラメータ

    par1

    The first parameter

    par2

    The second parameter

    which

    The flag to determine what to be calculated

    戻り値

    Returns CDF, x, or lambda, determined by which.

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    User Contributed Notes 1 note

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    s at nder dot com
    12 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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