/**
* Checks that resulting distribution of binary values is
* approximately same.
*
* @param string $bytes to check
*/
public static function pvalue($bytes)
{
$hist = array();
// histogram
$freq = array();
// expected frequency
$N = 256;
for ($i = 0; $i < $N; $i++) {
$hist[$i] = 0;
$freq[$i] = 1.0 / $N;
}
foreach (unpack('C*', $bytes) as $char) {
$hist[$char]++;
}
$chisqr = PearsonChiSquare::chiSquare($hist, $freq);
return PearsonChiSquare::pvalue($N - 1, $chisqr);
}
public function testPvalueHighPrecision()
{
$this->assertEquals(0.9906109591, PearsonChiSquare::pvalue(3, 0.11), '', 1.0E-9);
$this->assertEquals(0.9598403687, PearsonChiSquare::pvalue(7, 2), '', 1.0E-9);
$this->assertEquals(0.005569683073, PearsonChiSquare::pvalue(7, 20), '', 1.0E-9);
}