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authorGravatar Benoit Jacob <jacob.benoit.1@gmail.com>2009-10-28 18:19:29 -0400
committerGravatar Benoit Jacob <jacob.benoit.1@gmail.com>2009-10-28 18:19:29 -0400
commit2840ac7e948ecb3c7b19ba8f581f829a4a4e1fea (patch)
tree14adcd3aa33c4207b14455707bc247cea29029e6 /Eigen/src/QR/FullPivHouseholderQR.h
parent1f1c04cac1d8a87cbb34741d141df646b2da2827 (diff)
big huge changes, so i dont remember everything.
* renaming, e.g. LU ---> FullPivLU * split tests framework: more robust, e.g. dont generate empty tests if a number is skipped * make all remaining tests use that splitting, as needed. * Fix 4x4 inversion (see stable branch) * Transform::inverse() and geo_transform test : adapt to new inverse() API, it was also trying to instantiate inverse() for 3x4 matrices. * CMakeLists: more robust regexp to parse the version number * misc fixes in unit tests
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+// This file is part of Eigen, a lightweight C++ template library
+// for linear algebra.
+//
+// Copyright (C) 2008-2009 Gael Guennebaud <g.gael@free.fr>
+// Copyright (C) 2009 Benoit Jacob <jacob.benoit.1@gmail.com>
+//
+// Eigen is free software; you can redistribute it and/or
+// modify it under the terms of the GNU Lesser General Public
+// License as published by the Free Software Foundation; either
+// version 3 of the License, or (at your option) any later version.
+//
+// Alternatively, you can redistribute it and/or
+// modify it under the terms of the GNU General Public License as
+// published by the Free Software Foundation; either version 2 of
+// the License, or (at your option) any later version.
+//
+// Eigen is distributed in the hope that it will be useful, but WITHOUT ANY
+// WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+// FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License or the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public
+// License and a copy of the GNU General Public License along with
+// Eigen. If not, see <http://www.gnu.org/licenses/>.
+
+#ifndef EIGEN_FULLPIVOTINGHOUSEHOLDERQR_H
+#define EIGEN_FULLPIVOTINGHOUSEHOLDERQR_H
+
+/** \ingroup QR_Module
+ * \nonstableyet
+ *
+ * \class FullPivHouseholderQR
+ *
+ * \brief Householder rank-revealing QR decomposition of a matrix with full pivoting
+ *
+ * \param MatrixType the type of the matrix of which we are computing the QR decomposition
+ *
+ * This class performs a rank-revealing QR decomposition using Householder transformations.
+ *
+ * This decomposition performs a very prudent full pivoting in order to be rank-revealing and achieve optimal
+ * numerical stability. The trade-off is that it is slower than HouseholderQR and ColPivHouseholderQR.
+ *
+ * \sa MatrixBase::fullPivHouseholderQr()
+ */
+template<typename MatrixType> class FullPivHouseholderQR
+{
+ public:
+
+ enum {
+ RowsAtCompileTime = MatrixType::RowsAtCompileTime,
+ ColsAtCompileTime = MatrixType::ColsAtCompileTime,
+ Options = MatrixType::Options,
+ DiagSizeAtCompileTime = EIGEN_ENUM_MIN(ColsAtCompileTime,RowsAtCompileTime)
+ };
+
+ typedef typename MatrixType::Scalar Scalar;
+ typedef typename MatrixType::RealScalar RealScalar;
+ typedef Matrix<Scalar, RowsAtCompileTime, RowsAtCompileTime> MatrixQType;
+ typedef Matrix<Scalar, DiagSizeAtCompileTime, 1> HCoeffsType;
+ typedef Matrix<int, 1, ColsAtCompileTime> IntRowVectorType;
+ typedef Matrix<int, RowsAtCompileTime, 1> IntColVectorType;
+ typedef Matrix<Scalar, 1, ColsAtCompileTime> RowVectorType;
+ typedef Matrix<Scalar, RowsAtCompileTime, 1> ColVectorType;
+
+ /** \brief Default Constructor.
+ *
+ * The default constructor is useful in cases in which the user intends to
+ * perform decompositions via FullPivHouseholderQR::compute(const MatrixType&).
+ */
+ FullPivHouseholderQR() : m_isInitialized(false) {}
+
+ FullPivHouseholderQR(const MatrixType& matrix)
+ : m_isInitialized(false)
+ {
+ compute(matrix);
+ }
+
+ /** This method finds a solution x to the equation Ax=b, where A is the matrix of which
+ * *this is the QR decomposition, if any exists.
+ *
+ * \returns \c true if a solution exists, \c false if no solution exists.
+ *
+ * \param b the right-hand-side of the equation to solve.
+ *
+ * \param result a pointer to the vector/matrix in which to store the solution, if any exists.
+ * Resized if necessary, so that result->rows()==A.cols() and result->cols()==b.cols().
+ * If no solution exists, *result is left with undefined coefficients.
+ *
+ * \note The case where b is a matrix is not yet implemented. Also, this
+ * code is space inefficient.
+ *
+ * Example: \include FullPivHouseholderQR_solve.cpp
+ * Output: \verbinclude FullPivHouseholderQR_solve.out
+ */
+ template<typename OtherDerived, typename ResultType>
+ bool solve(const MatrixBase<OtherDerived>& b, ResultType *result) const;
+
+ MatrixQType matrixQ(void) const;
+
+ /** \returns a reference to the matrix where the Householder QR decomposition is stored
+ */
+ const MatrixType& matrixQR() const
+ {
+ ei_assert(m_isInitialized && "FullPivHouseholderQR is not initialized.");
+ return m_qr;
+ }
+
+ FullPivHouseholderQR& compute(const MatrixType& matrix);
+
+ const IntRowVectorType& colsPermutation() const
+ {
+ ei_assert(m_isInitialized && "FullPivHouseholderQR is not initialized.");
+ return m_cols_permutation;
+ }
+
+ const IntColVectorType& rowsTranspositions() const
+ {
+ ei_assert(m_isInitialized && "FullPivHouseholderQR is not initialized.");
+ return m_rows_transpositions;
+ }
+
+ /** \returns the absolute value of the determinant of the matrix of which
+ * *this is the QR decomposition. It has only linear complexity
+ * (that is, O(n) where n is the dimension of the square matrix)
+ * as the QR decomposition has already been computed.
+ *
+ * \note This is only for square matrices.
+ *
+ * \warning a determinant can be very big or small, so for matrices
+ * of large enough dimension, there is a risk of overflow/underflow.
+ * One way to work around that is to use logAbsDeterminant() instead.
+ *
+ * \sa logAbsDeterminant(), MatrixBase::determinant()
+ */
+ typename MatrixType::RealScalar absDeterminant() const;
+
+ /** \returns the natural log of the absolute value of the determinant of the matrix of which
+ * *this is the QR decomposition. It has only linear complexity
+ * (that is, O(n) where n is the dimension of the square matrix)
+ * as the QR decomposition has already been computed.
+ *
+ * \note This is only for square matrices.
+ *
+ * \note This method is useful to work around the risk of overflow/underflow that's inherent
+ * to determinant computation.
+ *
+ * \sa absDeterminant(), MatrixBase::determinant()
+ */
+ typename MatrixType::RealScalar logAbsDeterminant() const;
+
+ /** \returns the rank of the matrix of which *this is the QR decomposition.
+ *
+ * \note This is computed at the time of the construction of the QR decomposition. This
+ * method does not perform any further computation.
+ */
+ inline int rank() const
+ {
+ ei_assert(m_isInitialized && "FullPivHouseholderQR is not initialized.");
+ return m_rank;
+ }
+
+ /** \returns the dimension of the kernel of the matrix of which *this is the QR decomposition.
+ *
+ * \note Since the rank is computed at the time of the construction of the QR decomposition, this
+ * method almost does not perform any further computation.
+ */
+ inline int dimensionOfKernel() const
+ {
+ ei_assert(m_isInitialized && "FullPivHouseholderQR is not initialized.");
+ return m_qr.cols() - m_rank;
+ }
+
+ /** \returns true if the matrix of which *this is the QR decomposition represents an injective
+ * linear map, i.e. has trivial kernel; false otherwise.
+ *
+ * \note Since the rank is computed at the time of the construction of the QR decomposition, this
+ * method almost does not perform any further computation.
+ */
+ inline bool isInjective() const
+ {
+ ei_assert(m_isInitialized && "FullPivHouseholderQR is not initialized.");
+ return m_rank == m_qr.cols();
+ }
+
+ /** \returns true if the matrix of which *this is the QR decomposition represents a surjective
+ * linear map; false otherwise.
+ *
+ * \note Since the rank is computed at the time of the construction of the QR decomposition, this
+ * method almost does not perform any further computation.
+ */
+ inline bool isSurjective() const
+ {
+ ei_assert(m_isInitialized && "FullPivHouseholderQR is not initialized.");
+ return m_rank == m_qr.rows();
+ }
+
+ /** \returns true if the matrix of which *this is the QR decomposition is invertible.
+ *
+ * \note Since the rank is computed at the time of the construction of the QR decomposition, this
+ * method almost does not perform any further computation.
+ */
+ inline bool isInvertible() const
+ {
+ ei_assert(m_isInitialized && "FullPivHouseholderQR is not initialized.");
+ return isInjective() && isSurjective();
+ }
+
+ /** Computes the inverse of the matrix of which *this is the QR decomposition.
+ *
+ * \param result a pointer to the matrix into which to store the inverse. Resized if needed.
+ *
+ * \note If this matrix is not invertible, *result is left with undefined coefficients.
+ * Use isInvertible() to first determine whether this matrix is invertible.
+ *
+ * \sa inverse()
+ */
+ inline void computeInverse(MatrixType *result) const
+ {
+ ei_assert(m_isInitialized && "FullPivHouseholderQR is not initialized.");
+ ei_assert(m_qr.rows() == m_qr.cols() && "You can't take the inverse of a non-square matrix!");
+ solve(MatrixType::Identity(m_qr.rows(), m_qr.cols()), result);
+ }
+
+ /** \returns the inverse of the matrix of which *this is the QR decomposition.
+ *
+ * \note If this matrix is not invertible, the returned matrix has undefined coefficients.
+ * Use isInvertible() to first determine whether this matrix is invertible.
+ *
+ * \sa computeInverse()
+ */
+ inline MatrixType inverse() const
+ {
+ MatrixType result;
+ computeInverse(&result);
+ return result;
+ }
+
+ protected:
+ MatrixType m_qr;
+ HCoeffsType m_hCoeffs;
+ IntColVectorType m_rows_transpositions;
+ IntRowVectorType m_cols_permutation;
+ bool m_isInitialized;
+ RealScalar m_precision;
+ int m_rank;
+ int m_det_pq;
+};
+
+#ifndef EIGEN_HIDE_HEAVY_CODE
+
+template<typename MatrixType>
+typename MatrixType::RealScalar FullPivHouseholderQR<MatrixType>::absDeterminant() const
+{
+ ei_assert(m_isInitialized && "FullPivHouseholderQR is not initialized.");
+ ei_assert(m_qr.rows() == m_qr.cols() && "You can't take the determinant of a non-square matrix!");
+ return ei_abs(m_qr.diagonal().prod());
+}
+
+template<typename MatrixType>
+typename MatrixType::RealScalar FullPivHouseholderQR<MatrixType>::logAbsDeterminant() const
+{
+ ei_assert(m_isInitialized && "FullPivHouseholderQR is not initialized.");
+ ei_assert(m_qr.rows() == m_qr.cols() && "You can't take the determinant of a non-square matrix!");
+ return m_qr.diagonal().cwise().abs().cwise().log().sum();
+}
+
+template<typename MatrixType>
+FullPivHouseholderQR<MatrixType>& FullPivHouseholderQR<MatrixType>::compute(const MatrixType& matrix)
+{
+ int rows = matrix.rows();
+ int cols = matrix.cols();
+ int size = std::min(rows,cols);
+ m_rank = size;
+
+ m_qr = matrix;
+ m_hCoeffs.resize(size);
+
+ RowVectorType temp(cols);
+
+ m_precision = epsilon<Scalar>() * size;
+
+ m_rows_transpositions.resize(matrix.rows());
+ IntRowVectorType cols_transpositions(matrix.cols());
+ m_cols_permutation.resize(matrix.cols());
+ int number_of_transpositions = 0;
+
+ RealScalar biggest(0);
+
+ for (int k = 0; k < size; ++k)
+ {
+ int row_of_biggest_in_corner, col_of_biggest_in_corner;
+ RealScalar biggest_in_corner;
+
+ biggest_in_corner = m_qr.corner(Eigen::BottomRight, rows-k, cols-k)
+ .cwise().abs()
+ .maxCoeff(&row_of_biggest_in_corner, &col_of_biggest_in_corner);
+ row_of_biggest_in_corner += k;
+ col_of_biggest_in_corner += k;
+ if(k==0) biggest = biggest_in_corner;
+
+ // if the corner is negligible, then we have less than full rank, and we can finish early
+ if(ei_isMuchSmallerThan(biggest_in_corner, biggest, m_precision))
+ {
+ m_rank = k;
+ for(int i = k; i < size; i++)
+ {
+ m_rows_transpositions.coeffRef(i) = i;
+ cols_transpositions.coeffRef(i) = i;
+ m_hCoeffs.coeffRef(i) = Scalar(0);
+ }
+ break;
+ }
+
+ m_rows_transpositions.coeffRef(k) = row_of_biggest_in_corner;
+ cols_transpositions.coeffRef(k) = col_of_biggest_in_corner;
+ if(k != row_of_biggest_in_corner) {
+ m_qr.row(k).end(cols-k).swap(m_qr.row(row_of_biggest_in_corner).end(cols-k));
+ ++number_of_transpositions;
+ }
+ if(k != col_of_biggest_in_corner) {
+ m_qr.col(k).swap(m_qr.col(col_of_biggest_in_corner));
+ ++number_of_transpositions;
+ }
+
+ RealScalar beta;
+ m_qr.col(k).end(rows-k).makeHouseholderInPlace(&m_hCoeffs.coeffRef(k), &beta);
+ m_qr.coeffRef(k,k) = beta;
+
+ m_qr.corner(BottomRight, rows-k, cols-k-1)
+ .applyHouseholderOnTheLeft(m_qr.col(k).end(rows-k-1), m_hCoeffs.coeffRef(k), &temp.coeffRef(k+1));
+ }
+
+ for(int k = 0; k < matrix.cols(); ++k) m_cols_permutation.coeffRef(k) = k;
+ for(int k = 0; k < size; ++k)
+ std::swap(m_cols_permutation.coeffRef(k), m_cols_permutation.coeffRef(cols_transpositions.coeff(k)));
+
+ m_det_pq = (number_of_transpositions%2) ? -1 : 1;
+ m_isInitialized = true;
+
+ return *this;
+}
+
+template<typename MatrixType>
+template<typename OtherDerived, typename ResultType>
+bool FullPivHouseholderQR<MatrixType>::solve(
+ const MatrixBase<OtherDerived>& b,
+ ResultType *result
+) const
+{
+ ei_assert(m_isInitialized && "FullPivHouseholderQR is not initialized.");
+ result->resize(m_qr.cols(), b.cols());
+ if(m_rank==0)
+ {
+ if(b.squaredNorm() == RealScalar(0))
+ {
+ result->setZero();
+ return true;
+ }
+ else return false;
+ }
+
+ const int rows = m_qr.rows();
+ const int cols = b.cols();
+ ei_assert(b.rows() == rows);
+
+ typename OtherDerived::PlainMatrixType c(b);
+
+ Matrix<Scalar,1,MatrixType::ColsAtCompileTime> temp(cols);
+ for (int k = 0; k < m_rank; ++k)
+ {
+ int remainingSize = rows-k;
+ c.row(k).swap(c.row(m_rows_transpositions.coeff(k)));
+ c.corner(BottomRight, remainingSize, cols)
+ .applyHouseholderOnTheLeft(m_qr.col(k).end(remainingSize-1), m_hCoeffs.coeff(k), &temp.coeffRef(0));
+ }
+
+ if(!isSurjective())
+ {
+ // is c is in the image of R ?
+ RealScalar biggest_in_upper_part_of_c = c.corner(TopLeft, m_rank, c.cols()).cwise().abs().maxCoeff();
+ RealScalar biggest_in_lower_part_of_c = c.corner(BottomLeft, rows-m_rank, c.cols()).cwise().abs().maxCoeff();
+ if(!ei_isMuchSmallerThan(biggest_in_lower_part_of_c, biggest_in_upper_part_of_c, m_precision))
+ return false;
+ }
+ m_qr.corner(TopLeft, m_rank, m_rank)
+ .template triangularView<UpperTriangular>()
+ .solveInPlace(c.corner(TopLeft, m_rank, c.cols()));
+
+ for(int i = 0; i < m_rank; ++i) result->row(m_cols_permutation.coeff(i)) = c.row(i);
+ for(int i = m_rank; i < m_qr.cols(); ++i) result->row(m_cols_permutation.coeff(i)).setZero();
+ return true;
+}
+
+/** \returns the matrix Q */
+template<typename MatrixType>
+typename FullPivHouseholderQR<MatrixType>::MatrixQType FullPivHouseholderQR<MatrixType>::matrixQ() const
+{
+ ei_assert(m_isInitialized && "FullPivHouseholderQR is not initialized.");
+ // compute the product H'_0 H'_1 ... H'_n-1,
+ // where H_k is the k-th Householder transformation I - h_k v_k v_k'
+ // and v_k is the k-th Householder vector [1,m_qr(k+1,k), m_qr(k+2,k), ...]
+ int rows = m_qr.rows();
+ int cols = m_qr.cols();
+ int size = std::min(rows,cols);
+ MatrixQType res = MatrixQType::Identity(rows, rows);
+ Matrix<Scalar,1,MatrixType::RowsAtCompileTime> temp(rows);
+ for (int k = size-1; k >= 0; k--)
+ {
+ res.block(k, k, rows-k, rows-k)
+ .applyHouseholderOnTheLeft(m_qr.col(k).end(rows-k-1), ei_conj(m_hCoeffs.coeff(k)), &temp.coeffRef(k));
+ res.row(k).swap(res.row(m_rows_transpositions.coeff(k)));
+ }
+ return res;
+}
+
+#endif // EIGEN_HIDE_HEAVY_CODE
+
+/** \return the full-pivoting Householder QR decomposition of \c *this.
+ *
+ * \sa class FullPivHouseholderQR
+ */
+template<typename Derived>
+const FullPivHouseholderQR<typename MatrixBase<Derived>::PlainMatrixType>
+MatrixBase<Derived>::fullPivHouseholderQr() const
+{
+ return FullPivHouseholderQR<PlainMatrixType>(eval());
+}
+
+#endif // EIGEN_FULLPIVOTINGHOUSEHOLDERQR_H