src/Utilities/StringHelpers.cpp

0001 // This file is part of the ACTS project.
0002 //
0003 // Copyright (C) 2016 CERN for the benefit of the ACTS project
0004 //
0005 // This Source Code Form is subject to the terms of the Mozilla Public
0006 // License, v. 2.0. If a copy of the MPL was not distributed with this
0007 // file, You can obtain one at https://mozilla.org/MPL/2.0/.
0008
0009 #include "Acts/Utilities/StringHelpers.hpp"
0010
0011 #include <sstream>
0012
0013 #include <Eigen/Eigenvalues>
0014
0015 namespace Acts {
0016
0017 std::string printEigenDecomposition(
0018     const Eigen::Ref<const Eigen::MatrixXd>& mat) {
0019   // The matrix is assumed to be symmetric (e.g. a Hessian), so the
0020   // self-adjoint solver yields real eigen values and vectors and is
0021   // considerably cheaper to compile than the general Eigen::EigenSolver.
0022   Eigen::SelfAdjointEigenSolver<Eigen::MatrixXd> eigenDecomp{mat};
0023
0024   std::stringstream sstr{};
0025   sstr << "eigen values: " << eigenDecomp.eigenvalues().transpose();
0026   sstr << ", eigen vectors:\n" << eigenDecomp.eigenvectors();
0027   return sstr.str();
0028 }
0029
0030 }  // namespace Acts