PHP 8.4.0 Beta 5 available for testing

# stats_cdf_poisson

(PECL stats >= 1.0.0)

stats_cdf_poissonCalculates 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`.

`A simple poisson-distribution function, which only works for relatively small numbers (maximum of ~100/100 for most systems):<?phpfunction 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";?>`