Sequence of Householder reflections acting on subspaces with decreasing size.
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enum | { RowsAtCompileTime = internal::traits<HouseholderSequence>::RowsAtCompileTime
, ColsAtCompileTime = internal::traits<HouseholderSequence>::ColsAtCompileTime
, MaxRowsAtCompileTime = internal::traits<HouseholderSequence>::MaxRowsAtCompileTime
, MaxColsAtCompileTime = internal::traits<HouseholderSequence>::MaxColsAtCompileTime
} |
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typedef internal::traits< HouseholderSequence >::Scalar | Scalar |
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typedef HouseholderSequence< typename internal::conditional< NumTraits< Scalar >::IsComplex, typename internal::remove_all< typename VectorsType::ConjugateReturnType >::type, VectorsType >::type, typename internal::conditional< NumTraits< Scalar >::IsComplex, typename internal::remove_all< typename CoeffsType::ConjugateReturnType >::type, CoeffsType >::type, Side > | ConjugateReturnType |
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typedef HouseholderSequence< VectorsType, typename internal::conditional< NumTraits< Scalar >::IsComplex, typename internal::remove_all< typename CoeffsType::ConjugateReturnType >::type, CoeffsType >::type, Side > | AdjointReturnType |
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typedef HouseholderSequence< typename internal::conditional< NumTraits< Scalar >::IsComplex, typename internal::remove_all< typename VectorsType::ConjugateReturnType >::type, VectorsType >::type, CoeffsType, Side > | TransposeReturnType |
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typedef HouseholderSequence< typename internal::add_const< VectorsType >::type, typename internal::add_const< CoeffsType >::type, Side > | ConstHouseholderSequence |
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typedef Eigen::Index | Index |
| The interface type of indices. More...
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typedef internal::traits< HouseholderSequence< VectorsType, CoeffsType, Side > >::StorageKind | StorageKind |
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EIGEN_DEVICE_FUNC | HouseholderSequence (const VectorsType &v, const CoeffsType &h) |
| Constructor. More...
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EIGEN_DEVICE_FUNC | HouseholderSequence (const HouseholderSequence &other) |
| Copy constructor. More...
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EIGEN_DEVICE_FUNC EIGEN_CONSTEXPR Index | rows () const EIGEN_NOEXCEPT |
| Number of rows of transformation viewed as a matrix. More...
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EIGEN_DEVICE_FUNC EIGEN_CONSTEXPR Index | cols () const EIGEN_NOEXCEPT |
| Number of columns of transformation viewed as a matrix. More...
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EIGEN_DEVICE_FUNC const EssentialVectorType | essentialVector (Index k) const |
| Essential part of a Householder vector. More...
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TransposeReturnType | transpose () const |
| Transpose of the Householder sequence. More...
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ConjugateReturnType | conjugate () const |
| Complex conjugate of the Householder sequence. More...
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template<bool Cond> |
EIGEN_DEVICE_FUNC internal::conditional< Cond, ConjugateReturnType, ConstHouseholderSequence >::type | conjugateIf () const |
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AdjointReturnType | adjoint () const |
| Adjoint (conjugate transpose) of the Householder sequence. More...
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AdjointReturnType | inverse () const |
| Inverse of the Householder sequence (equals the adjoint). More...
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template<typename DestType > |
EIGEN_DEVICE_FUNC void | evalTo (DestType &dst) const |
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template<typename Dest , typename Workspace > |
EIGEN_DEVICE_FUNC void | evalTo (Dest &dst, Workspace &workspace) const |
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template<typename Dest > |
void | applyThisOnTheRight (Dest &dst) const |
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template<typename Dest , typename Workspace > |
void | applyThisOnTheRight (Dest &dst, Workspace &workspace) const |
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template<typename Dest > |
void | applyThisOnTheLeft (Dest &dst, bool inputIsIdentity=false) const |
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template<typename Dest , typename Workspace > |
void | applyThisOnTheLeft (Dest &dst, Workspace &workspace, bool inputIsIdentity=false) const |
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template<typename OtherDerived > |
internal::matrix_type_times_scalar_type< Scalar, OtherDerived >::Type | operator* (const MatrixBase< OtherDerived > &other) const |
| Computes the product of a Householder sequence with a matrix. More...
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EIGEN_DEVICE_FUNC HouseholderSequence & | setLength (Index length) |
| Sets the length of the Householder sequence. More...
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EIGEN_DEVICE_FUNC HouseholderSequence & | setShift (Index shift) |
| Sets the shift of the Householder sequence. More...
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EIGEN_DEVICE_FUNC Index | length () const |
| Returns the length of the Householder sequence. More...
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EIGEN_DEVICE_FUNC Index | shift () const |
| Returns the shift of the Householder sequence. More...
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EIGEN_DEVICE_FUNC HouseholderSequence< VectorsType, CoeffsType, Side > & | derived () |
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EIGEN_DEVICE_FUNC const HouseholderSequence< VectorsType, CoeffsType, Side > & | derived () const |
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EIGEN_DEVICE_FUNC HouseholderSequence< VectorsType, CoeffsType, Side > & | const_cast_derived () const |
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EIGEN_DEVICE_FUNC const HouseholderSequence< VectorsType, CoeffsType, Side > & | const_derived () const |
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EIGEN_DEVICE_FUNC EIGEN_CONSTEXPR Index | rows () const EIGEN_NOEXCEPT |
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EIGEN_DEVICE_FUNC EIGEN_CONSTEXPR Index | cols () const EIGEN_NOEXCEPT |
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EIGEN_DEVICE_FUNC EIGEN_CONSTEXPR Index | size () const EIGEN_NOEXCEPT |
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EIGEN_DEVICE_FUNC void | evalTo (Dest &dst) const |
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EIGEN_DEVICE_FUNC void | addTo (Dest &dst) const |
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EIGEN_DEVICE_FUNC void | subTo (Dest &dst) const |
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EIGEN_DEVICE_FUNC void | applyThisOnTheRight (Dest &dst) const |
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EIGEN_DEVICE_FUNC void | applyThisOnTheLeft (Dest &dst) const |
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template<typename VectorsType, typename CoeffsType, int Side>
class Eigen::HouseholderSequence< VectorsType, CoeffsType, Side >
Sequence of Householder reflections acting on subspaces with decreasing size.
\householder_module
- Template Parameters
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VectorsType | type of matrix containing the Householder vectors |
CoeffsType | type of vector containing the Householder coefficients |
Side | either OnTheLeft (the default) or OnTheRight |
This class represents a product sequence of Householder reflections where the first Householder reflection acts on the whole space, the second Householder reflection leaves the one-dimensional subspace spanned by the first unit vector invariant, the third Householder reflection leaves the two-dimensional subspace spanned by the first two unit vectors invariant, and so on up to the last reflection which leaves all but one dimensions invariant and acts only on the last dimension. Such sequences of Householder reflections are used in several algorithms to zero out certain parts of a matrix. Indeed, the methods HessenbergDecomposition::matrixQ(), Tridiagonalization::matrixQ(), HouseholderQR::householderQ(), and ColPivHouseholderQR::householderQ() all return a HouseholderSequence.
More precisely, the class HouseholderSequence represents an
matrix
of the form
where the i-th Householder reflection is
. The i-th Householder coefficient
is a scalar and the i-th Householder vector
is a vector of the form
The last
entries of
are called the essential part of the Householder vector.
Typical usages are listed below, where H is a HouseholderSequence:
A.applyOnTheRight(H);
A.applyOnTheLeft(H);
A.applyOnTheRight(H.adjoint());
A.applyOnTheLeft(H.adjoint());
MatrixXd Q = H;
In addition to the adjoint, you can also apply the inverse (=adjoint), the transpose, and the conjugate operators.
See the documentation for HouseholderSequence(const VectorsType&, const CoeffsType&) for an example.
- See also
- MatrixBase::applyOnTheLeft(), MatrixBase::applyOnTheRight()