MatrixVs& MatrixVs::multiply(const MatrixVs& rhs) noexcept(false) {
    if(n_col_ != rhs.n_row_) throw std::invalid_argument("Cannot multiply matrices with these parameters");
    MatrixVs res(this->rowCount(), rhs.colCount());
    for (std::ptrdiff_t i = 0; i < this->rowCount(); ++i){
        for (std::ptrdiff_t j = 0; j < rhs.colCount(); ++j){
            res.at(i, j) = 0;
            for (std::ptrdiff_t k = 0; k < rhs.rowCount(); ++k){
                res.at(i, j) += this->at(i, k) * rhs.at(k, j);
            }
        }
    }
    (*this) = res;
    return (*this);
}