/**
* Cross product (AxB)
* https://en.wikipedia.org/wiki/Cross_product
*
* | i j k |
* A x B = | a₀ a₁ a₂ | = |a₁ a₂| - |a₀ a₂| + |a₀ a₁|
* | b₀ b₁ b₂ | |b₁ b₂|i |b₀ b₂|j |b₀ b₁|k
*
* = (a₁b₂ - b₁a₂) - (a₀b₂ - b₀a₂) + (a₀b₁ - b₀a₁)
*
* @param Vector $B
*
* @return Vector
*/
public function crossProduct(Vector $B)
{
if ($B->getN() !== 3 || $this->n !== 3) {
throw new Exception\VectorException('Vectors must have 3 items');
}
$s1 = $this->A[1] * $B[2] - $this->A[2] * $B[1];
$s2 = -($this->A[0] * $B[2] - $this->A[2] * $B[0]);
$s3 = $this->A[0] * $B[1] - $this->A[1] * $B[0];
return new Vector([$s1, $s2, $s3]);
}
