\( \newcommand{\E}{\mathrm{E}} \) \( \newcommand{\A}{\mathrm{A}} \) \( \newcommand{\R}{\mathrm{R}} \) \( \newcommand{\N}{\mathrm{N}} \) \( \newcommand{\Q}{\mathrm{Q}} \) \( \newcommand{\Z}{\mathrm{Z}} \) \( \def\ccSum #1#2#3{ \sum_{#1}^{#2}{#3} } \def\ccProd #1#2#3{ \sum_{#1}^{#2}{#3} }\)
CGAL 4.11.2 - CGAL and Solvers
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Solver_interface/diagonalize_matrix.cpp
#include <iostream>
#ifdef CGAL_EIGEN3_ENABLED
#include <CGAL/Eigen_diagonalize_traits.h>
#else
#include <CGAL/Diagonalize_traits.h>
#endif
typedef double FT;
typedef CGAL::cpp11::array<FT, 6> Eigen_matrix;
typedef CGAL::cpp11::array<FT, 3> Eigen_vector;
typedef CGAL::cpp11::array<FT, 9> Eigen_three_vectors;
// If Eigen is enabled, use it, otherwise fallback to the internal model
#ifdef CGAL_EIGEN3_ENABLED
typedef CGAL::Eigen_diagonalize_traits<FT, 3> Diagonalize_traits;
#else
typedef CGAL::Diagonalize_traits<FT, 3> Diagonalize_traits;
#endif
int main(void)
{
Eigen_matrix covariance = {{ 0., 0., 0., 0., 0., 0. }};
// Fill matrix with random numbers
for (std::size_t i = 0; i < 6; ++ i)
covariance[i] = rand ();
Eigen_vector eigenvalues;
Eigen_three_vectors eigenvectors;
if (!(Diagonalize_traits::diagonalize_selfadjoint_covariance_matrix (covariance,
eigenvalues,
eigenvectors)))
{
std::cerr << "Error: cannot diagonalize matrix" << std::endl;
return -1;
}
// Print result
for (std::size_t i = 0; i < 3; ++ i)
{
std::cout << "Eigenvalue " << i+1 << " = " << eigenvalues[i] << std::endl
<< " with eigenvector [ ";
for (std::size_t j = 0; j < 3; ++ j)
std::cout << eigenvectors[3*i + j] << " ";
std::cout << "]" << std::endl;
}
return 0;
}