/**
Returns the cumulative distribution function, the probability of getting the test value or something below it
@param float $x The test value
@param float $k Shape parameter
@return float The probability
*/
static function getCdf($x, $k = 1)
{
return \PHPStats\Stats::lowerGamma($k / 2.0, $x / 2) / \PHPStats\Stats::gamma($k / 2.0);
}
/**
Returns the cumulative distribution function, the probability of getting the test value or something below it
@param float $x The test value
@param float $k Shape parameter
@param float $theta Scale parameter
@return float The probability
*/
static function getCdf($x, $k = 1, $theta = 1)
{
return \PHPStats\Stats::lowerGamma($k, $x / $theta) / \PHPStats\Stats::gamma($k);
}
public function test_lowerGamma()
{
$this->assertEquals(0.1606, round(Stats::lowerGamma(3, 1), 5));
$this->assertEquals(0.6466499999999999, round(Stats::lowerGamma(3, 2), 5));
$this->assertEquals(0.91237, round(Stats::lowerGamma(3, 2.5), 5));
$this->assertEquals(400.07089, round(Stats::lowerGamma(10, 3), 5));
$this->assertEquals(2951.02827, round(Stats::lowerGamma(10, 4), 5));
$this->assertEquals(11549.76544, round(Stats::lowerGamma(10, 5), 5));
$this->assertEquals(30454.34729, round(Stats::lowerGamma(10, 6), 5));
}
