public function crossProduct(Vector $other)
{
if ($this->length() != 3) {
throw new Exception("Must be 3 dimension");
}
if ($other->length() != 3) {
throw new Exception("Must be 3 dimension");
}
$class = get_called_class();
$result = new $class();
/* @var $result Vector */
$result->value = array($this->value[1] * $other->value[2] - $this->value[2] * $other->value[1], $this->value[2] * $other->value[0] - $this->value[0] * $other->value[2], $this->value[0] * $other->value[1] - $this->value[1] * $other->value[0]);
return $result;
}
/**
* Axiom: |projᵇA|² + |perpᵇA|² = |A|²
* Sum of squared lengths of proj and perp equals squared length of A
* @dataProvider dataProviderForProjPerp
*/
public function testProjPerpSumOfSquares(array $A, array $B)
{
$A = new Vector($A);
$B = new Vector($B);
$│A│² = $A->length() ** 2;
$│projᵇA│² = $A->projection($B)->length() ** 2;
$│perpᵇA│² = $A->perp($B)->length() ** 2;
$this->assertEquals($│A│², $│projᵇA│² + $│perpᵇA│²);
}
/**
* @dataProvider dataProviderForLength
*/
public function testLength(array $A, $l²norm)
{
$A = new Vector($A);
$this->assertEquals($l²norm, $A->length(), '', 0.0001);
}
/**
* @covers webd\vectors\Vector::length
*/
public function testLength()
{
$this->assertEquals(3, $this->object->length());
}
/**
* Returns the angle between the two vectors.
*
* @param Vector $b The vector to compute the angle between.
* @return float The angle between the two vectors in radians.
* @throws \Exception if either of the vectors are zero-length.
* @throws \Exception if the vectors are not in the same vector space.
* @see checkVectorSpace() For Exception information.
*/
public function angleBetween(Vector $b)
{
$denominator = $this->length() * $b->length();
if ($denominator == 0) {
throw new \Exception('Cannot divide by zero');
}
return acos($this->dotProduct($b) / $denominator);
}
