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bug #1592: makes partial min/max reductions trigger an assertion on inputs with a zero reduction length (+doc and tests)

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This commit is contained in:
Gael Guennebaud
2019-01-15 15:13:24 +01:00
parent f8bc5cb39e
commit 027e44ed24
3 changed files with 59 additions and 3 deletions
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36
Eigen/src/Core/VectorwiseOp.h
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@@ -173,6 +173,14 @@ struct member_redux {
* Example: \include MatrixBase_colwise_iterator_cxx11.cpp
* Output: \verbinclude MatrixBase_colwise_iterator_cxx11.out
*
* For a partial reduction on an empty input, some rules apply.
* For the sake of clarity, let's consider a vertical reduction:
* - If the number of columns is zero, then a 1x0 row-major vector expression is returned.
* - Otherwise, if the number of rows is zero, then
* - a row vector of zeros is returned for sum-like reductions (sum, squaredNorm, norm, etc.)
* - a row vector of ones is returned for a product reduction (e.g., <code>MatrixXd(n,0).colwise().prod()</code>)
* - an assert is triggered for all other reductions (minCoeff,maxCoeff,redux(bin_op))
*
* \sa DenseBase::colwise(), DenseBase::rowwise(), class PartialReduxExpr
*/
template<typename ExpressionType, int Direction> class VectorwiseOp
@@ -294,13 +302,19 @@ template<typename ExpressionType, int Direction> class VectorwiseOp
* The template parameter \a BinaryOp is the type of the functor
* of the custom redux operator. Note that func must be an associative operator.
*
* \warning the size along the reduction direction must be strictly positive,
* otherwise an assertion is triggered.
*
* \sa class VectorwiseOp, DenseBase::colwise(), DenseBase::rowwise()
*/
template<typename BinaryOp>
EIGEN_DEVICE_FUNC
const typename ReduxReturnType<BinaryOp>::Type
redux(const BinaryOp& func = BinaryOp()) const
{ return typename ReduxReturnType<BinaryOp>::Type(_expression(), internal::member_redux<BinaryOp,Scalar>(func)); }
{
eigen_assert(redux_length()>0 && "you are using an empty matrix");
return typename ReduxReturnType<BinaryOp>::Type(_expression(), internal::member_redux<BinaryOp,Scalar>(func));
}
typedef typename ReturnType<internal::member_minCoeff>::Type MinCoeffReturnType;
typedef typename ReturnType<internal::member_maxCoeff>::Type MaxCoeffReturnType;
@@ -325,6 +339,9 @@ template<typename ExpressionType, int Direction> class VectorwiseOp
/** \returns a row (or column) vector expression of the smallest coefficient
* of each column (or row) of the referenced expression.
*
* \warning the size along the reduction direction must be strictly positive,
* otherwise an assertion is triggered.
*
* \warning the result is undefined if \c *this contains NaN.
*
* Example: \include PartialRedux_minCoeff.cpp
@@ -333,11 +350,17 @@ template<typename ExpressionType, int Direction> class VectorwiseOp
* \sa DenseBase::minCoeff() */
EIGEN_DEVICE_FUNC
const MinCoeffReturnType minCoeff() const
{ return MinCoeffReturnType(_expression()); }
{
eigen_assert(redux_length()>0 && "you are using an empty matrix");
return MinCoeffReturnType(_expression());
}
/** \returns a row (or column) vector expression of the largest coefficient
* of each column (or row) of the referenced expression.
*
* \warning the size along the reduction direction must be strictly positive,
* otherwise an assertion is triggered.
*
* \warning the result is undefined if \c *this contains NaN.
*
* Example: \include PartialRedux_maxCoeff.cpp
@@ -346,7 +369,10 @@ template<typename ExpressionType, int Direction> class VectorwiseOp
* \sa DenseBase::maxCoeff() */
EIGEN_DEVICE_FUNC
const MaxCoeffReturnType maxCoeff() const
{ return MaxCoeffReturnType(_expression()); }
{
eigen_assert(redux_length()>0 && "you are using an empty matrix");
return MaxCoeffReturnType(_expression());
}
/** \returns a row (or column) vector expression of the squared norm
* of each column (or row) of the referenced expression.
@@ -690,6 +716,10 @@ template<typename ExpressionType, int Direction> class VectorwiseOp
const HNormalizedReturnType hnormalized() const;
protected:
Index redux_length() const
{
return Direction==Vertical ? m_matrix.rows() : m_matrix.cols();
}
ExpressionTypeNested m_matrix;
};