Makes diagonal tensor(matrix).

You can find more information in comments below.

template<class TYPE, size_t SIZE>
    void diagonal(TTensor<TYPE, SIZE, SIZE> &m, const TYPE value); // Makes diagonal(with specified value) NxN tensor(matrix) 
    
    template<class TYPE, size_t SIZE>
    void diagonal(TTensor<TYPE, SIZE, SIZE> &m, const std::initializer_list<TYPE> &values); // Populate diagonal values with specified one. Set 1 for rest if size of values is less then diagonal element count. Set non-diagonal elements to zero