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Change return type of matrixH() method to HouseholderSequence.

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This method is a member of Tridiagonalization and HessenbergDecomposition.
This commit is contained in:
Jitse Niesen
2010-05-24 17:35:54 +01:00
parent 76dd0e5314
commit eb3ca68684
5 changed files with 92 additions and 81 deletions
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57
Eigen/src/Eigenvalues/Tridiagonalization.h
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@@ -2,6 +2,7 @@
// for linear algebra.
//
// Copyright (C) 2008 Gael Guennebaud <g.gael@free.fr>
// Copyright (C) 2010 Jitse Niesen <jitse@maths.leeds.ac.uk>
//
// Eigen is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
@@ -61,7 +62,9 @@ template<typename _MatrixType> class Tridiagonalization
{
public:
/** \brief Synonym for the template parameter \p _MatrixType. */
typedef _MatrixType MatrixType;
typedef typename MatrixType::Scalar Scalar;
typedef typename NumTraits<Scalar>::Real RealScalar;
@@ -89,6 +92,9 @@ template<typename _MatrixType> class Tridiagonalization
Block<MatrixType,SizeMinusOne,SizeMinusOne>,0 >
>::ret SubDiagonalReturnType;
/** \brief Return type of matrixQ() */
typedef typename HouseholderSequence<MatrixType,CoeffVectorType>::ConjugateReturnType HouseholderSequenceType;
/** \brief Default constructor.
*
* \param [in] size Positive integer, size of the matrix whose tridiagonal
@@ -195,29 +201,25 @@ template<typename _MatrixType> class Tridiagonalization
*/
inline const MatrixType& packedMatrix() const { return m_matrix; }
/** \brief Reconstructs the unitary matrix Q in the decomposition
/** \brief Returns the unitary matrix Q in the decomposition
*
* \returns the matrix Q
* \returns object representing the matrix Q
*
* \pre Either the constructor Tridiagonalization(const MatrixType&) or
* the member function compute(const MatrixType&) has been called before
* to compute the tridiagonal decomposition of a matrix.
*
* This function reconstructs the matrix Q from the Householder
* coefficients and the packed matrix stored internally. This
* reconstruction requires \f$ 4n^3 / 3 \f$ flops.
* This function returns a light-weight object of template class
* HouseholderSequence. You can either apply it directly to a matrix or
* you can convert it to a matrix of type #MatrixType.
*
* \sa Tridiagonalization(const MatrixType&) for an example,
* matrixT(), matrixQInPlace()
* matrixT(), class HouseholderSequence
*/
MatrixType matrixQ() const;
/** \brief Reconstructs the unitary matrix Q in the decomposition
*
* This is an in-place variant of matrixQ() which avoids the copy.
* This function will probably be deleted soon.
*/
template<typename QDerived> void matrixQInPlace(MatrixBase<QDerived>* q) const;
HouseholderSequenceType matrixQ() const
{
return HouseholderSequenceType(m_matrix, m_hCoeffs.conjugate(), false, m_matrix.rows() - 1, 1);
}
/** \brief Constructs the tridiagonal matrix T in the decomposition
*
@@ -386,31 +388,6 @@ void Tridiagonalization<MatrixType>::_compute(MatrixType& matA, CoeffVectorType&
}
}
template<typename MatrixType>
typename Tridiagonalization<MatrixType>::MatrixType
Tridiagonalization<MatrixType>::matrixQ() const
{
MatrixType matQ;
matrixQInPlace(&matQ);
return matQ;
}
template<typename MatrixType>
template<typename QDerived>
void Tridiagonalization<MatrixType>::matrixQInPlace(MatrixBase<QDerived>* q) const
{
QDerived& matQ = q->derived();
int n = m_matrix.rows();
matQ = MatrixType::Identity(n,n);
typedef typename ei_plain_row_type<MatrixType>::type RowVectorType;
RowVectorType aux(n);
for (int i = n-2; i>=0; i--)
{
matQ.bottomRightCorner(n-i-1,n-i-1)
.applyHouseholderOnTheLeft(m_matrix.col(i).tail(n-i-2), ei_conj(m_hCoeffs.coeff(i)), &aux.coeffRef(0,0));
}
}
template<typename MatrixType>
void Tridiagonalization<MatrixType>::decomposeInPlace(MatrixType& mat, DiagonalType& diag, SubDiagonalType& subdiag, bool extractQ)
{
@@ -426,7 +403,7 @@ void Tridiagonalization<MatrixType>::decomposeInPlace(MatrixType& mat, DiagonalT
diag = tridiag.diagonal();
subdiag = tridiag.subDiagonal();
if (extractQ)
tridiag.matrixQInPlace(&mat);
mat = tridiag.matrixQ();
}
}