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PermutationMatrix: add inverse() and product of permutations

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This commit is contained in:
Benoit Jacob 2009-11-16 09:39:07 -05:00
parent e09768e3bc
commit b25eb5fdaa
2 changed files with 36 additions and 3 deletions
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30
Eigen/src/Core/PermutationMatrix.h
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@ -105,10 +105,10 @@ class PermutationMatrix : public AnyMatrixBase<PermutationMatrix<SizeAtCompileTi
ei_assert(rows == cols); ei_assert(rows == cols);
} }
/** \returns the number of columns */ /** \returns the number of rows */
inline int rows() const { return m_indices.size(); } inline int rows() const { return m_indices.size(); }
/** \returns the number of rows */ /** \returns the number of columns */
inline int cols() const { return m_indices.size(); } inline int cols() const { return m_indices.size(); }
template<typename DenseDerived> template<typename DenseDerived>
@ -126,7 +126,31 @@ class PermutationMatrix : public AnyMatrixBase<PermutationMatrix<SizeAtCompileTi
const IndicesType& indices() const { return m_indices; } const IndicesType& indices() const { return m_indices; }
IndicesType& indices() { return m_indices; } IndicesType& indices() { return m_indices; }
/**** inversion and multiplication helpers to hopefully get RVO ****/
protected:
enum Inverse_t {Inverse};
PermutationMatrix(Inverse_t, const PermutationMatrix& other)
: m_indices(other.m_indices.size())
{
for (int i=0; i<rows();++i) m_indices.coeffRef(other.m_indices.coeff(i)) = i;
}
enum Product_t {Product};
PermutationMatrix(Product_t, const PermutationMatrix& lhs, const PermutationMatrix& rhs)
: m_indices(lhs.m_indices.size())
{
ei_assert(lhs.cols() == rhs.rows());
for (int i=0; i<rows();++i) m_indices.coeffRef(i) = lhs.m_indices.coeff(rhs.m_indices.coeff(i));
}
public:
inline PermutationMatrix inverse() const
{ return PermutationMatrix(Inverse, *this); }
template<int OtherSize, int OtherMaxSize>
inline PermutationMatrix operator*(const PermutationMatrix<OtherSize, OtherMaxSize>& other) const
{ return PermutationMatrix(Product, *this, other); }
protected: protected:
IndicesType m_indices; IndicesType m_indices;

9
test/permutationmatrices.cpp
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@ -72,6 +72,15 @@ template<typename MatrixType> void permutationmatrices(const MatrixType& m)
Matrix<Scalar,Cols,Cols> rm(rp); Matrix<Scalar,Cols,Cols> rm(rp);
VERIFY_IS_APPROX(m_permuted, lm*m_original*rm); VERIFY_IS_APPROX(m_permuted, lm*m_original*rm);
VERIFY_IS_APPROX(lp.inverse()*m_permuted*rp.inverse(), m_original);
VERIFY((lp*lp.inverse()).toDenseMatrix().isIdentity());
LeftPermutationVectorType lv2;
randomPermutationVector(lv2, rows);
LeftPermutationType lp2(lv2);
Matrix<Scalar,Rows,Rows> lm2(lp2);
VERIFY_IS_APPROX((lp*lp2).toDenseMatrix().template cast<Scalar>(), lm2*lm);
} }
void test_permutationmatrices() void test_permutationmatrices()