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# stats_cdf_poisson

(PECL stats >= 1.0.0)

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

### Descrição

float stats_cdf_poisson ( float `\$par1` , float `\$par2` , int `\$which` )

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 cumurative 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

### Parâmetros

`par1`

The first parameter

`par2`

The second parameter

`which`

The flag to determine what to be calculated

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

### User Contributed Notes 1 note

s at nder dot com
5 years ago
``` 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";?> ```