Tridiagonalization.hpp

/*
 * Copyright 2025 INRIA
 */

#ifndef __eigenpy_decompositions_tridiagonalization_hpp__
#define __eigenpy_decompositions_tridiagonalization_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 TridiagonalizationVisitor : public boost::python::def_visitor<
 TridiagonalizationVisitor<_MatrixType>> {
 typedef _MatrixType MatrixType;
 typedef typename MatrixType::Scalar Scalar;
 typedef Eigen::Tridiagonalization<MatrixType> Solver;
 typedef Eigen::VectorXd VectorType;

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

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

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

 .def(
 "matrixQ",
 +[](const Solver &c) -> MatrixType { return c.matrixQ(); },
 "Returns the unitary matrix Q in the decomposition.")
 .def(
 "matrixT",
 +[](const Solver &c) -> MatrixType { return c.matrixT(); },
 "Returns an expression of the tridiagonal matrix T in the "
 "decomposition.")

 .def(
 "diagonal",
 +[](const Solver &c) -> VectorType { return c.diagonal(); },
 bp::arg("self"),
 "Returns the diagonal of the tridiagonal matrix T in the "
 "decomposition. ")

 .def(
 "subDiagonal",
 +[](const Solver &c) -> VectorType { return c.subDiagonal(); },
 bp::arg("self"),
 "Returns the subdiagonal of the tridiagonal matrix T in the "
 "decomposition.");
 }

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

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

} // namespace eigenpy

#endif // ifndef __eigenpy_decompositions_tridiagonalization_hpp__