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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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42
Eigen/src/Eigenvalues/HessenbergDecomposition.h
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@@ -2,6 +2,7 @@
// for linear algebra.
//
// Copyright (C) 2008-2009 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
@@ -59,7 +60,9 @@ template<typename _MatrixType> class HessenbergDecomposition
{
public:
/** \brief Synonym for the template parameter \p _MatrixType. */
typedef _MatrixType MatrixType;
enum {
Size = MatrixType::RowsAtCompileTime,
SizeMinusOne = Size == Dynamic ? Dynamic : Size - 1,
@@ -68,17 +71,20 @@ template<typename _MatrixType> class HessenbergDecomposition
MaxSizeMinusOne = MaxSize == Dynamic ? Dynamic : MaxSize - 1
};
/** \brief Scalar type for matrices of type \p _MatrixType. */
/** \brief Scalar type for matrices of type #MatrixType. */
typedef typename MatrixType::Scalar Scalar;
/** \brief Type for vector of Householder coefficients.
*
* This is column vector with entries of type #Scalar. The length of the
* vector is one less than the size of \p _MatrixType, if it is a
* fixed-side type.
* vector is one less than the size of #MatrixType, if it is a fixed-side
* type.
*/
typedef Matrix<Scalar, SizeMinusOne, 1, Options & ~RowMajor, MaxSizeMinusOne, 1> CoeffVectorType;
/** \brief Return type of matrixQ() */
typedef typename HouseholderSequence<MatrixType,CoeffVectorType>::ConjugateReturnType HouseholderSequenceType;
/** \brief Default constructor; the decomposition will be computed later.
*
* \param [in] size The size of the matrix whose Hessenberg decomposition will be computed.
@@ -190,19 +196,22 @@ template<typename _MatrixType> class HessenbergDecomposition
/** \brief Reconstructs the orthogonal matrix Q in the decomposition
*
* \returns the matrix Q
* \returns object representing the matrix Q
*
* \pre Either the constructor HessenbergDecomposition(const MatrixType&)
* or the member function compute(const MatrixType&) has been called
* before to compute the Hessenberg 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 matrixH() for an example
* \sa matrixH() for an example, class HouseholderSequence
*/
MatrixType matrixQ() const;
HouseholderSequenceType matrixQ() const
{
return HouseholderSequenceType(m_matrix, m_hCoeffs.conjugate(), false, m_matrix.rows() - 1, 1);
}
/** \brief Constructs the Hessenberg matrix H in the decomposition
*
@@ -281,21 +290,6 @@ void HessenbergDecomposition<MatrixType>::_compute(MatrixType& matA, CoeffVector
}
}
template<typename MatrixType>
typename HessenbergDecomposition<MatrixType>::MatrixType
HessenbergDecomposition<MatrixType>::matrixQ() const
{
int n = m_matrix.rows();
MatrixType matQ = MatrixType::Identity(n,n);
VectorType temp(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)), &temp.coeffRef(0,0));
}
return matQ;
}
#endif // EIGEN_HIDE_HEAVY_CODE
template<typename MatrixType>