/home/sm958/Work/pele/source/pele/matrix.h

#ifndef _PELE_MATRIX_H_
#define _PELE_MATRIX_H_

namespace pele{

template<class dtype>
class MatrixAdapter : public pele::Array<dtype> {
public:
    size_t _dim2;

    MatrixAdapter(size_t dim1, size_t dim2, dtype val=0)
        : pele::Array<dtype>(dim1 * dim2, val),
          _dim2(dim2)
    {}

    MatrixAdapter(pele::Array<double> v, size_t dim2)
        : pele::Array<dtype>(v),
          _dim2(dim2)
    {
        if (v.size() % dim2 != 0) {
            throw std::invalid_argument("v.size() is not divisible by dim2");
        }
    }

    MatrixAdapter(double * data, size_t dim1, size_t dim2)
        : pele::Array<dtype>(data, dim1*dim2),
          _dim2(dim2)
    {}

    inline dtype const & operator()(size_t i, size_t j) const
    {
        return this->operator[](i * _dim2 + j);
    }
    inline dtype & operator()(size_t i, size_t j)
    {
        return this->operator[](i * _dim2 + j);
    }

    inline std::pair<size_t, size_t> shape() const
    {
        return std::pair<size_t, size_t>(this->size() / _dim2, _dim2);
    }
};

template<class dtype>
MatrixAdapter<dtype> hacky_mat_mul(MatrixAdapter<dtype> const & A, MatrixAdapter<dtype> const & B)
{
    assert(A.shape().second == B.shape().first);
    size_t const L = A.shape().second;
    size_t const N = A.shape().first;
    size_t const M = B.shape().second;

    MatrixAdapter<dtype> C(N, M, 0);
    for (size_t i = 0; i<N; ++i){
        for (size_t j = 0; j<M; ++j){
            double val = 0;
            for (size_t k = 0; k<L; ++k){
                val += A(i,k) * B(k,j);
            }
            C(i,j) = val;
        }
    }
    return C;
}

// * multiply a matrix times an vector
// */
//template<class dtype>
//pele::Array<dtype> hacky_mat_mul(MatrixAdapter<dtype> const & A, pele::Array<dtype> const & v)
//{
//    assert(A.shape().second == v.size());
//    size_t const L = A.shape().second;
//    size_t const n = A.shape().first;
//
//    pele::Array<dtype> C(n, 0);
//    for (size_t i = 0; i<n; ++i){
//        dtype val = 0;
//        for (size_t k = 0; k<L; ++k){
//            val += A(i,k) * v[k];
//        }
//        C(i) = val;
//    }
//    return C;
//}

}
#endif