I am new to Eigen and not so experienced in c++ so go slow on me.

I am trying to implement a generic kronecker product function but the compiler is throwing an error. It seems to have a problem using a local templated matrix.

So my code is

Code: Select all

template<typename T>
MatrixBase<T> kron(const MatrixBase<T>& A, const MatrixBase<T>& B)
{
   MatrixBase<T> C(A.rows()*B.rows(),A.cols()*B.cols());
   
   for(int i=0; i<A.cols(); i++)
   {
      for(int j=0; j<A.rows(); j++)
      {
         C.block(i*B.rows(),j*B.cols(),B.rows(),B.cols())=A(i,j)*B;
      }
   }
}


and the error is pointing at the instantiation of C:

/usr/local/include/Eigen/src/Core/MatrixBase.h:513:5: error: ‘Eigen::MatrixBase<Derived>::MatrixBase(int, int) [with Derived = Eigen::Matrix<double, -0x00000000000000001, -0x00000000000000001>]’ is private


Can someone help me get this working?

a MAtrixBase<> is more like an abstract class, you have to return a Matrix<> object. Note that there is a kronecker product implementation in unsupported/Eigen/KroneckerProduct

Thanks, will check out the implementation and if I understand this correctly MatrixBase<> cannot be instantiated but Matrix<> can.