MathPHP\LinearAlgebra\Matrix::rowSubtract PHP Method

    public function rowSubtract(int $mᵢ, int $mⱼ, $k) : Matrix
    {
        if ($mᵢ >= $this->m || $mⱼ >= $this->m) {
            throw new Exception\MatrixException('Row to subtract does not exist');
        }
        $n = $this->n;
        $R = $this->A;
        for ($j = 0; $j < $n; $j++) {
            $R[$mⱼ][$j] -= $R[$mᵢ][$j] * $k;
        }
        return MatrixFactory::create($R);
    }