/**
Returns the probability mass function
@param float $x The test value
@param float $lambda The rate of events
@return float The probability
*/
static function getPmf($x, $lambda = 1)
{
return exp(-$lambda) * pow($lambda, $x) / \PHPStats\Stats::factorial($x);
}
public function test_factorial()
{
$this->assertEquals(1, Stats::factorial(0));
$this->assertEquals(1, Stats::factorial(1));
$this->assertEquals(2, Stats::factorial(2));
$this->assertEquals(120, Stats::factorial(5));
$this->assertEquals(3628800, Stats::factorial(10));
}
