/** * Axiom: L(n,2) = (n - 1)n! / 2 * Lah number identity when k is 2 * * @dataProvider dataProivderForLahNumberIdentities */ public function testLahNumberIdentityKEqualsTwo(int $n) { // Skip exception where n < k if ($n === 1) { return; } $L⟮n、1⟯ = Combinatorics::lahNumber($n, 2); $⟮n−1⟯n!/2 = ($n - 1) * Combinatorics::factorial($n) / 2; $this->assertEquals($L⟮n、1⟯, $⟮n−1⟯n!/2); }
public function testFactorialBoundsException() { $this->setExpectedException('MathPHP\\Exception\\OutOfBoundsException'); Combinatorics::factorial(-1); }