public function testLower()
{
$lower = $this->getDecomposition()->lower();
static::assertEquals(1, $lower->get(0, 0));
static::assertEquals(0, $lower->get(0, 1));
static::assertEquals(0, $lower->get(0, 2));
static::assertEquals(0, $lower->get(0, 3));
static::assertEquals(3, $lower->get(1, 0));
static::assertEquals(1, $lower->get(1, 1));
static::assertEquals(0, $lower->get(1, 2));
static::assertEquals(0, $lower->get(1, 3));
static::assertEquals(1, $lower->get(2, 0));
static::assertEquals(4, $lower->get(2, 1));
static::assertEquals(1, $lower->get(2, 2));
static::assertEquals(0, $lower->get(2, 3));
static::assertEquals(2, $lower->get(3, 0));
static::assertEquals(1, $lower->get(3, 1));
static::assertEquals(7, $lower->get(3, 2));
static::assertEquals(1, $lower->get(3, 3));
}