HessenbergDecomposition.hpp

/*
 * Copyright 2025 INRIA
 */

#ifndef __eigenpy_decompositions_hessenberg_decomposition_hpp__
#define __eigenpy_decompositions_hessenberg_decomposition_hpp__

#include <Eigen/Core>
#include <Eigen/Eigenvalues>

#include "eigenpy/eigen-to-python.hpp"
#include "eigenpy/eigenpy.hpp"
#include "eigenpy/utils/scalar-name.hpp"

namespace eigenpy {

template <typename _MatrixType>
struct HessenbergDecompositionVisitor
 : public boost::python::def_visitor<
 HessenbergDecompositionVisitor<_MatrixType>> {
 typedef _MatrixType MatrixType;
 typedef typename MatrixType::Scalar Scalar;
 typedef Eigen::HessenbergDecomposition<MatrixType> Solver;

 template <class PyClass>
 void visit(PyClass& cl) const {
 cl
 .def(bp::init<Eigen::DenseIndex>(
 bp::arg("size"),
 "Default constructor; the decomposition will be computed later. "))
 .def(bp::init<MatrixType>(
 bp::arg("matrix"),
 "Constructor; computes Hessenberg decomposition of given matrix. "))

 .def(
 "compute",
 (Solver & (Solver::*)(const Eigen::EigenBase<MatrixType>& matrix)) &
 Solver::compute,
 bp::args("self", "A"),
 "Computes Hessenberg decomposition of given matrix. ",
 bp::return_self<>())

 .def("householderCoefficients", &Solver::householderCoefficients,
 bp::arg("self"), "Returns the Householder coefficients. ",
 bp::return_value_policy<bp::copy_const_reference>())

 .def(
 "matrixQ",
 +[](const Solver& c) -> MatrixType { return c.matrixQ(); },
 "Reconstructs the orthogonal matrix Q in the decomposition.")
 .def(
 "matrixH",
 +[](const Solver& c) -> MatrixType { return c.matrixH(); },
 "Constructs the Hessenberg matrix H in the decomposition.")

 .def("packedMatrix", &Solver::packedMatrix, bp::arg("self"),
 "Returns the internal representation of the decomposition. ",
 bp::return_value_policy<bp::copy_const_reference>());
 }

 static void expose() {
 static const std::string classname =
 "HessenbergDecomposition" + scalar_name<Scalar>::shortname();
 expose(classname);
 }

 static void expose(const std::string& name) {
 bp::class_<Solver>(name.c_str(), bp::no_init)
 .def(HessenbergDecompositionVisitor())
 .def(IdVisitor<Solver>());
 }
};

} // namespace eigenpy

#endif // ifndef __eigenpy_decompositions_hessenberg_decomposition_hpp__