public function testAbsReturnsAbsoluteValue()
{
$c1 = new ComplexType($this->createRationalType(1), $this->createRationalType(2));
$c2 = new ComplexType($this->createRationalType(-1), $this->createRationalType(2));
$c3 = new ComplexType($this->createRationalType(1), $this->createRationalType(-2));
$c4 = new ComplexType($this->createRationalType(-1), $this->createRationalType(-2));
$this->assertEquals($c1->modulus(), $c1->abs());
$this->assertEquals($c1->modulus(), $c2->abs());
$this->assertEquals($c1->modulus(), $c3->abs());
$this->assertEquals($c1->modulus(), $c4->abs());
}
