eigen library selfadjointView problem

Question

I am persistently getting error messages whenever I try to use the selfadjointView property of any matrix or sparse matrix using the eigen library. Below is a simple code to check that. In my program I do try with self-adjoint matrix:

#define EIGEN_YES_I_KNOW_SPARSE_MODULE_IS_NOT_STABLE_YET
#include <Eigen/Sparse>
#include <Eigen/Dense>
#include <Eigen/Core>
#include <iostream>

using namespace Eigen;
int main ()
{
SparseMatrix<float>  mat(3,3);
Matrix<float, 3, 1> vec;
std::cout<<mat.selfadjointView<>()*vec;
}

The error message I get is: error: no matching function for call to ‚'Eigen::SparseMatrix::selfadjointView()‚

Answer 1

You have to specify the template argument, so it should read mat.selfadjointView<Upper>() or mat.selfadjointView<Lower>() . The first one means that it should use the entries in the upper triangular part of mat and fill the lower triangular part to make the matrix self-adjoint. The second one is the other way around.