add minor to Eigen2Support

2026-04-10 11:34:33 +08:00 · 2010-04-22 20:49:01 -04:00
parent 2362eadcdd
commit a4f9ca44ab
6 changed files with 135 additions and 0 deletions
--- a/Eigen/src/Eigen2Support/Minor.h
+++ b/Eigen/src/Eigen2Support/Minor.h
@@ -0,0 +1,124 @@
+// This file is part of Eigen, a lightweight C++ template library
+// for linear algebra.
+//
+// Copyright (C) 2006-2009 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_MINOR_H
+#define EIGEN_MINOR_H
+
+/** \nonstableyet
+  * \class Minor
+  *
+  * \brief Expression of a minor
+  *
+  * \param MatrixType the type of the object in which we are taking a minor
+  *
+  * This class represents an expression of a minor. It is the return
+  * type of MatrixBase::minor() and most of the time this is the only way it
+  * is used.
+  *
+  * \sa MatrixBase::minor()
+  */
+template<typename MatrixType>
+struct ei_traits<Minor<MatrixType> >
+ : ei_traits<MatrixType>
+{
+  typedef typename ei_nested<MatrixType>::type MatrixTypeNested;
+  typedef typename ei_unref<MatrixTypeNested>::type _MatrixTypeNested;
+  enum {
+    RowsAtCompileTime = (MatrixType::RowsAtCompileTime != Dynamic) ?
+                          int(MatrixType::RowsAtCompileTime) - 1 : Dynamic,
+    ColsAtCompileTime = (MatrixType::ColsAtCompileTime != Dynamic) ?
+                          int(MatrixType::ColsAtCompileTime) - 1 : Dynamic,
+    MaxRowsAtCompileTime = (MatrixType::MaxRowsAtCompileTime != Dynamic) ?
+                             int(MatrixType::MaxRowsAtCompileTime) - 1 : Dynamic,
+    MaxColsAtCompileTime = (MatrixType::MaxColsAtCompileTime != Dynamic) ?
+                             int(MatrixType::MaxColsAtCompileTime) - 1 : Dynamic,
+    Flags = _MatrixTypeNested::Flags & HereditaryBits,
+    CoeffReadCost = _MatrixTypeNested::CoeffReadCost // minor is used typically on tiny matrices,
+      // where loops are unrolled and the 'if' evaluates at compile time
+  };
+};
+
+template<typename MatrixType> class Minor
+  : public MatrixBase<Minor<MatrixType> >
+{
+  public:
+
+    typedef MatrixBase<Minor> Base;
+    EIGEN_DENSE_PUBLIC_INTERFACE(Minor)
+
+    inline Minor(const MatrixType& matrix,
+                       int row, int col)
+      : m_matrix(matrix), m_row(row), m_col(col)
+    {
+      ei_assert(row >= 0 && row < matrix.rows()
+          && col >= 0 && col < matrix.cols());
+    }
+
+    EIGEN_INHERIT_ASSIGNMENT_OPERATORS(Minor)
+
+    inline int rows() const { return m_matrix.rows() - 1; }
+    inline int cols() const { return m_matrix.cols() - 1; }
+
+    inline Scalar& coeffRef(int row, int col)
+    {
+      return m_matrix.const_cast_derived().coeffRef(row + (row >= m_row), col + (col >= m_col));
+    }
+
+    inline const Scalar coeff(int row, int col) const
+    {
+      return m_matrix.coeff(row + (row >= m_row), col + (col >= m_col));
+    }
+
+  protected:
+    const typename MatrixType::Nested m_matrix;
+    const int m_row, m_col;
+};
+
+/** \nonstableyet
+  * \return an expression of the (\a row, \a col)-minor of *this,
+  * i.e. an expression constructed from *this by removing the specified
+  * row and column.
+  *
+  * Example: \include MatrixBase_minor.cpp
+  * Output: \verbinclude MatrixBase_minor.out
+  *
+  * \sa class Minor
+  */
+template<typename Derived>
+inline Minor<Derived>
+MatrixBase<Derived>::minor(int row, int col)
+{
+  return Minor<Derived>(derived(), row, col);
+}
+
+/** \nonstableyet
+  * This is the const version of minor(). */
+template<typename Derived>
+inline const Minor<Derived>
+MatrixBase<Derived>::minor(int row, int col) const
+{
+  return Minor<Derived>(derived(), row, col);
+}
+
+#endif // EIGEN_MINOR_H