MOAB  4.9.3pre
Eigen::SVDBase< Derived > Class Template Reference

Base class of SVD algorithms. More...

#include <SVDBase.h>

Inheritance diagram for Eigen::SVDBase< Derived >:
Collaboration diagram for Eigen::SVDBase< Derived >:

List of all members.

Public Types

enum  {
  RowsAtCompileTime = MatrixType::RowsAtCompileTime, ColsAtCompileTime = MatrixType::ColsAtCompileTime, DiagSizeAtCompileTime = EIGEN_SIZE_MIN_PREFER_DYNAMIC(RowsAtCompileTime,ColsAtCompileTime), MaxRowsAtCompileTime = MatrixType::MaxRowsAtCompileTime,
  MaxColsAtCompileTime = MatrixType::MaxColsAtCompileTime, MaxDiagSizeAtCompileTime = EIGEN_SIZE_MIN_PREFER_FIXED(MaxRowsAtCompileTime,MaxColsAtCompileTime), MatrixOptions = MatrixType::Options
}
typedef internal::traits
< Derived >::MatrixType 
MatrixType
typedef MatrixType::Scalar Scalar
typedef NumTraits< typename
MatrixType::Scalar >::Real 
RealScalar
typedef MatrixType::StorageIndex StorageIndex
typedef Eigen::Index Index
typedef Matrix< Scalar,
RowsAtCompileTime,
RowsAtCompileTime,
MatrixOptions,
MaxRowsAtCompileTime,
MaxRowsAtCompileTime
MatrixUType
typedef Matrix< Scalar,
ColsAtCompileTime,
ColsAtCompileTime,
MatrixOptions,
MaxColsAtCompileTime,
MaxColsAtCompileTime
MatrixVType
typedef
internal::plain_diag_type
< MatrixType, RealScalar >
::type 
SingularValuesType

Public Member Functions

Derived & derived ()
const Derived & derived () const
const MatrixUTypematrixU () const
const MatrixVTypematrixV () const
const SingularValuesTypesingularValues () const
Index nonzeroSingularValues () const
Index rank () const
Derived & setThreshold (const RealScalar &threshold)
Derived & setThreshold (Default_t)
RealScalar threshold () const
bool computeU () const
bool computeV () const
Index rows () const
Index cols () const
template<typename Rhs >
const Solve< Derived, Rhs > solve (const MatrixBase< Rhs > &b) const
template<typename RhsType , typename DstType >
EIGEN_DEVICE_FUNC void _solve_impl (const RhsType &rhs, DstType &dst) const

Protected Member Functions

bool allocate (Index rows, Index cols, unsigned int computationOptions)
 SVDBase ()
 Default Constructor.

Static Protected Member Functions

static void check_template_parameters ()

Protected Attributes

MatrixUType m_matrixU
MatrixVType m_matrixV
SingularValuesType m_singularValues
bool m_isInitialized
bool m_isAllocated
bool m_usePrescribedThreshold
bool m_computeFullU
bool m_computeThinU
bool m_computeFullV
bool m_computeThinV
unsigned int m_computationOptions
Index m_nonzeroSingularValues
Index m_rows
Index m_cols
Index m_diagSize
RealScalar m_prescribedThreshold

Detailed Description

template<typename Derived>
class Eigen::SVDBase< Derived >

Base class of SVD algorithms.

Template Parameters:
Derivedthe type of the actual SVD decomposition

SVD decomposition consists in decomposing any n-by-p matrix A as a product

\[ A = U S V^* \]

where U is a n-by-n unitary, V is a p-by-p unitary, and S is a n-by-p real positive matrix which is zero outside of its main diagonal; the diagonal entries of S are known as the singular values of A and the columns of U and V are known as the left and right singular vectors of A respectively.

Singular values are always sorted in decreasing order.

You can ask for only thin U or V to be computed, meaning the following. In case of a rectangular n-by-p matrix, letting m be the smaller value among n and p, there are only m singular vectors; the remaining columns of U and V do not correspond to actual singular vectors. Asking for thin U or V means asking for only their m first columns to be formed. So U is then a n-by-m matrix, and V is then a p-by-m matrix. Notice that thin U and V are all you need for (least squares) solving.

If the input matrix has inf or nan coefficients, the result of the computation is undefined, but the computation is guaranteed to terminate in finite (and reasonable) time.

See also:
class BDCSVD, class JacobiSVD

Definition at line 48 of file SVDBase.h.


Member Typedef Documentation

template<typename Derived>
typedef Eigen::Index Eigen::SVDBase< Derived >::Index
Deprecated:
since Eigen 3.3

Definition at line 56 of file SVDBase.h.

template<typename Derived>
typedef internal::traits<Derived>::MatrixType Eigen::SVDBase< Derived >::MatrixType
template<typename Derived>
typedef NumTraits<typename MatrixType::Scalar>::Real Eigen::SVDBase< Derived >::RealScalar
template<typename Derived>
typedef MatrixType::Scalar Eigen::SVDBase< Derived >::Scalar
template<typename Derived>
typedef MatrixType::StorageIndex Eigen::SVDBase< Derived >::StorageIndex

Definition at line 55 of file SVDBase.h.


Member Enumeration Documentation

template<typename Derived>
anonymous enum
Enumerator:
RowsAtCompileTime 
ColsAtCompileTime 
DiagSizeAtCompileTime 
MaxRowsAtCompileTime 
MaxColsAtCompileTime 
MaxDiagSizeAtCompileTime 
MatrixOptions 

Definition at line 57 of file SVDBase.h.


Constructor & Destructor Documentation

template<typename Derived>
Eigen::SVDBase< Derived >::SVDBase ( ) [inline, protected]

Default Constructor.

Default constructor of SVDBase

Definition at line 244 of file SVDBase.h.


Member Function Documentation

template<typename Derived >
template<typename RhsType , typename DstType >
void Eigen::SVDBase< Derived >::_solve_impl ( const RhsType &  rhs,
DstType &  dst 
) const

Definition at line 260 of file SVDBase.h.

{
  eigen_assert(rhs.rows() == rows());

  // A = U S V^*
  // So A^{-1} = V S^{-1} U^*

  Matrix<Scalar, Dynamic, RhsType::ColsAtCompileTime, 0, MatrixType::MaxRowsAtCompileTime, RhsType::MaxColsAtCompileTime> tmp;
  Index l_rank = rank();
  tmp.noalias() =  m_matrixU.leftCols(l_rank).adjoint() * rhs;
  tmp = m_singularValues.head(l_rank).asDiagonal().inverse() * tmp;
  dst = m_matrixV.leftCols(l_rank) * tmp;
}
template<typename MatrixType >
bool Eigen::SVDBase< MatrixType >::allocate ( Index  rows,
Index  cols,
unsigned int  computationOptions 
) [protected]

Reimplemented in Eigen::JacobiSVD< _MatrixType, QRPreconditioner >, and Eigen::BDCSVD< _MatrixType >.

Definition at line 276 of file SVDBase.h.

{
  eigen_assert(rows >= 0 && cols >= 0);

  if (m_isAllocated &&
      rows == m_rows &&
      cols == m_cols &&
      computationOptions == m_computationOptions)
  {
    return true;
  }

  m_rows = rows;
  m_cols = cols;
  m_isInitialized = false;
  m_isAllocated = true;
  m_computationOptions = computationOptions;
  m_computeFullU = (computationOptions & ComputeFullU) != 0;
  m_computeThinU = (computationOptions & ComputeThinU) != 0;
  m_computeFullV = (computationOptions & ComputeFullV) != 0;
  m_computeThinV = (computationOptions & ComputeThinV) != 0;
  eigen_assert(!(m_computeFullU && m_computeThinU) && "SVDBase: you can't ask for both full and thin U");
  eigen_assert(!(m_computeFullV && m_computeThinV) && "SVDBase: you can't ask for both full and thin V");
  eigen_assert(EIGEN_IMPLIES(m_computeThinU || m_computeThinV, MatrixType::ColsAtCompileTime==Dynamic) &&
           "SVDBase: thin U and V are only available when your matrix has a dynamic number of columns.");

  m_diagSize = (std::min)(m_rows, m_cols);
  m_singularValues.resize(m_diagSize);
  if(RowsAtCompileTime==Dynamic)
    m_matrixU.resize(m_rows, m_computeFullU ? m_rows : m_computeThinU ? m_diagSize : 0);
  if(ColsAtCompileTime==Dynamic)
    m_matrixV.resize(m_cols, m_computeFullV ? m_cols : m_computeThinV ? m_diagSize : 0);

  return false;
}
template<typename Derived>
static void Eigen::SVDBase< Derived >::check_template_parameters ( ) [inline, static, protected]

Definition at line 222 of file SVDBase.h.

template<typename Derived>
Index Eigen::SVDBase< Derived >::cols ( void  ) const [inline]

Definition at line 194 of file SVDBase.h.

{ return m_cols; }
template<typename Derived>
bool Eigen::SVDBase< Derived >::computeU ( ) const [inline]
Returns:
true if U (full or thin) is asked for in this SVD decomposition

Definition at line 189 of file SVDBase.h.

template<typename Derived>
bool Eigen::SVDBase< Derived >::computeV ( ) const [inline]
Returns:
true if V (full or thin) is asked for in this SVD decomposition

Definition at line 191 of file SVDBase.h.

template<typename Derived>
Derived& Eigen::SVDBase< Derived >::derived ( ) [inline]

Definition at line 71 of file SVDBase.h.

{ return *static_cast<Derived*>(this); }
template<typename Derived>
const Derived& Eigen::SVDBase< Derived >::derived ( ) const [inline]

Definition at line 72 of file SVDBase.h.

{ return *static_cast<const Derived*>(this); }
template<typename Derived>
const MatrixUType& Eigen::SVDBase< Derived >::matrixU ( ) const [inline]
Returns:
the U matrix.

For the SVD decomposition of a n-by-p matrix, letting m be the minimum of n and p, the U matrix is n-by-n if you asked for ComputeFullU , and is n-by-m if you asked for ComputeThinU .

The m first columns of U are the left singular vectors of the matrix being decomposed.

This method asserts that you asked for U to be computed.

Definition at line 83 of file SVDBase.h.

  {
    eigen_assert(m_isInitialized && "SVD is not initialized.");
    eigen_assert(computeU() && "This SVD decomposition didn't compute U. Did you ask for it?");
    return m_matrixU;
  }
template<typename Derived>
const MatrixVType& Eigen::SVDBase< Derived >::matrixV ( ) const [inline]
Returns:
the V matrix.

For the SVD decomposition of a n-by-p matrix, letting m be the minimum of n and p, the V matrix is p-by-p if you asked for ComputeFullV , and is p-by-m if you asked for ComputeThinV .

The m first columns of V are the right singular vectors of the matrix being decomposed.

This method asserts that you asked for V to be computed.

Definition at line 99 of file SVDBase.h.

  {
    eigen_assert(m_isInitialized && "SVD is not initialized.");
    eigen_assert(computeV() && "This SVD decomposition didn't compute V. Did you ask for it?");
    return m_matrixV;
  }
template<typename Derived>
Index Eigen::SVDBase< Derived >::nonzeroSingularValues ( ) const [inline]
Returns:
the number of singular values that are not exactly 0

Definition at line 118 of file SVDBase.h.

  {
    eigen_assert(m_isInitialized && "SVD is not initialized.");
    return m_nonzeroSingularValues;
  }
template<typename Derived>
Index Eigen::SVDBase< Derived >::rank ( ) const [inline]
Returns:
the rank of the matrix of which *this is the SVD.
Note:
This method has to determine which singular values should be considered nonzero. For that, it uses the threshold value that you can control by calling setThreshold(const RealScalar&).

Definition at line 130 of file SVDBase.h.

  {
    using std::abs;
    using std::max;
    eigen_assert(m_isInitialized && "JacobiSVD is not initialized.");
    if(m_singularValues.size()==0) return 0;
    RealScalar premultiplied_threshold = (max)(m_singularValues.coeff(0) * threshold(), (std::numeric_limits<RealScalar>::min)());
    Index i = m_nonzeroSingularValues-1;
    while(i>=0 && m_singularValues.coeff(i) < premultiplied_threshold) --i;
    return i+1;
  }
template<typename Derived>
Index Eigen::SVDBase< Derived >::rows ( void  ) const [inline]

Definition at line 193 of file SVDBase.h.

{ return m_rows; }
template<typename Derived>
Derived& Eigen::SVDBase< Derived >::setThreshold ( const RealScalar threshold) [inline]

Allows to prescribe a threshold to be used by certain methods, such as rank() and solve(), which need to determine when singular values are to be considered nonzero. This is not used for the SVD decomposition itself.

When it needs to get the threshold value, Eigen calls threshold(). The default is NumTraits<Scalar>::epsilon()

Parameters:
thresholdThe new value to use as the threshold.

A singular value will be considered nonzero if its value is strictly greater than $ \vert singular value \vert \leqslant threshold \times \vert max singular value \vert $.

If you want to come back to the default behavior, call setThreshold(Default_t)

Definition at line 156 of file SVDBase.h.

template<typename Derived>
Derived& Eigen::SVDBase< Derived >::setThreshold ( Default_t  ) [inline]

Allows to come back to the default behavior, letting Eigen use its default formula for determining the threshold.

You should pass the special object Eigen::Default as parameter here.

 svd.setThreshold(Eigen::Default); 

See the documentation of setThreshold(const RealScalar&).

Definition at line 171 of file SVDBase.h.

  {
    m_usePrescribedThreshold = false;
    return derived();
  }
template<typename Derived>
const SingularValuesType& Eigen::SVDBase< Derived >::singularValues ( ) const [inline]
Returns:
the vector of singular values.

For the SVD decomposition of a n-by-p matrix, letting m be the minimum of n and p, the returned vector has size m. Singular values are always sorted in decreasing order.

Definition at line 111 of file SVDBase.h.

  {
    eigen_assert(m_isInitialized && "SVD is not initialized.");
    return m_singularValues;
  }
template<typename Derived>
template<typename Rhs >
const Solve<Derived, Rhs> Eigen::SVDBase< Derived >::solve ( const MatrixBase< Rhs > &  b) const [inline]
Returns:
a (least squares) solution of $ A x = b $ using the current SVD decomposition of A.
Parameters:
bthe right-hand-side of the equation to solve.
Note:
Solving requires both U and V to be computed. Thin U and V are enough, there is no need for full U or V.
SVD solving is implicitly least-squares. Thus, this method serves both purposes of exact solving and least-squares solving. In other words, the returned solution is guaranteed to minimize the Euclidean norm $ \Vert A x - b \Vert $.

Definition at line 207 of file SVDBase.h.

  {
    eigen_assert(m_isInitialized && "SVD is not initialized.");
    eigen_assert(computeU() && computeV() && "SVD::solve() requires both unitaries U and V to be computed (thin unitaries suffice).");
    return Solve<Derived, Rhs>(derived(), b.derived());
  }
template<typename Derived>
RealScalar Eigen::SVDBase< Derived >::threshold ( ) const [inline]

Returns the threshold that will be used by certain methods such as rank().

See the documentation of setThreshold(const RealScalar&).

Definition at line 181 of file SVDBase.h.

  {
    eigen_assert(m_isInitialized || m_usePrescribedThreshold);
    return m_usePrescribedThreshold ? m_prescribedThreshold
                                    : (std::max<Index>)(1,m_diagSize)*NumTraits<Scalar>::epsilon();
  }

Member Data Documentation

template<typename Derived>
Index Eigen::SVDBase< Derived >::m_cols [protected]

Definition at line 237 of file SVDBase.h.

template<typename Derived>
unsigned int Eigen::SVDBase< Derived >::m_computationOptions [protected]

Definition at line 236 of file SVDBase.h.

template<typename Derived>
bool Eigen::SVDBase< Derived >::m_computeFullU [protected]

Definition at line 234 of file SVDBase.h.

template<typename Derived>
bool Eigen::SVDBase< Derived >::m_computeFullV [protected]

Definition at line 235 of file SVDBase.h.

template<typename Derived>
bool Eigen::SVDBase< Derived >::m_computeThinU [protected]

Definition at line 234 of file SVDBase.h.

template<typename Derived>
bool Eigen::SVDBase< Derived >::m_computeThinV [protected]

Definition at line 235 of file SVDBase.h.

template<typename Derived>
Index Eigen::SVDBase< Derived >::m_diagSize [protected]

Definition at line 237 of file SVDBase.h.

template<typename Derived>
bool Eigen::SVDBase< Derived >::m_isAllocated [protected]

Definition at line 233 of file SVDBase.h.

template<typename Derived>
bool Eigen::SVDBase< Derived >::m_isInitialized [protected]

Definition at line 233 of file SVDBase.h.

template<typename Derived>
MatrixUType Eigen::SVDBase< Derived >::m_matrixU [protected]

Definition at line 230 of file SVDBase.h.

template<typename Derived>
MatrixVType Eigen::SVDBase< Derived >::m_matrixV [protected]

Definition at line 231 of file SVDBase.h.

template<typename Derived>
Index Eigen::SVDBase< Derived >::m_nonzeroSingularValues [protected]

Definition at line 237 of file SVDBase.h.

template<typename Derived>
RealScalar Eigen::SVDBase< Derived >::m_prescribedThreshold [protected]

Definition at line 238 of file SVDBase.h.

template<typename Derived>
Index Eigen::SVDBase< Derived >::m_rows [protected]

Definition at line 237 of file SVDBase.h.

template<typename Derived>
SingularValuesType Eigen::SVDBase< Derived >::m_singularValues [protected]

Definition at line 232 of file SVDBase.h.

template<typename Derived>
bool Eigen::SVDBase< Derived >::m_usePrescribedThreshold [protected]

Definition at line 233 of file SVDBase.h.


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