public function add(self $vector) : self
{
if ($this->dimension() !== $vector->dimension()) {
throw new VectorsMustMeOfTheSameDimensionException();
}
$vector->rewind();
$numbers = $this->numbers->reduce([], function (array $numbers, float $number) use($vector) : array {
$numbers[] = $number + $vector->current();
$vector->next();
return $numbers;
});
return new self(...$numbers);
}
public function testSum()
{
$vector = new Vector(1, 2, 3, -4);
$this->assertSame(2.0, $vector->sum());
}
