diff options
| -rw-r--r-- | Eigen/src/Core/VectorwiseOp.h | 8 | ||||
| -rw-r--r-- | doc/C07_TutorialReductionsVisitorsBroadcasting.dox | 19 |
2 files changed, 21 insertions, 6 deletions
diff --git a/Eigen/src/Core/VectorwiseOp.h b/Eigen/src/Core/VectorwiseOp.h index 7819cb489..e8a905043 100644 --- a/Eigen/src/Core/VectorwiseOp.h +++ b/Eigen/src/Core/VectorwiseOp.h @@ -561,7 +561,7 @@ template<typename ExpressionType, int Direction> class VectorwiseOp * Example: \include MatrixBase_colwise.cpp * Output: \verbinclude MatrixBase_colwise.out * - * \sa rowwise(), class VectorwiseOp + * \sa rowwise(), class VectorwiseOp, \ref TutorialReductionsVisitorsBroadcasting */ template<typename Derived> inline const typename DenseBase<Derived>::ConstColwiseReturnType @@ -572,7 +572,7 @@ DenseBase<Derived>::colwise() const /** \returns a writable VectorwiseOp wrapper of *this providing additional partial reduction operations * - * \sa rowwise(), class VectorwiseOp + * \sa rowwise(), class VectorwiseOp, \ref TutorialReductionsVisitorsBroadcasting */ template<typename Derived> inline typename DenseBase<Derived>::ColwiseReturnType @@ -586,7 +586,7 @@ DenseBase<Derived>::colwise() * Example: \include MatrixBase_rowwise.cpp * Output: \verbinclude MatrixBase_rowwise.out * - * \sa colwise(), class VectorwiseOp + * \sa colwise(), class VectorwiseOp, \ref TutorialReductionsVisitorsBroadcasting */ template<typename Derived> inline const typename DenseBase<Derived>::ConstRowwiseReturnType @@ -597,7 +597,7 @@ DenseBase<Derived>::rowwise() const /** \returns a writable VectorwiseOp wrapper of *this providing additional partial reduction operations * - * \sa colwise(), class VectorwiseOp + * \sa colwise(), class VectorwiseOp, \ref TutorialReductionsVisitorsBroadcasting */ template<typename Derived> inline typename DenseBase<Derived>::RowwiseReturnType diff --git a/doc/C07_TutorialReductionsVisitorsBroadcasting.dox b/doc/C07_TutorialReductionsVisitorsBroadcasting.dox index e58ff6e2c..f3879b8b9 100644 --- a/doc/C07_TutorialReductionsVisitorsBroadcasting.dox +++ b/doc/C07_TutorialReductionsVisitorsBroadcasting.dox @@ -191,12 +191,27 @@ This can be accomplished with: \verbinclude Tutorial_ReductionsVisitorsBroadcasting_broadcast_simple.out </td></tr></table> +We can interpret the instruction <tt>mat.colwise() += v</tt> in two equivalent ways. It adds the vector \c v +to every column of the matrix. Alternatively, it can be interpreted as repeating the vector \c v four times to +form a four-by-two matrix which is then added to \c mat: +\f[ +\begin{bmatrix} 1 & 2 & 6 & 9 \\ 3 & 1 & 7 & 2 \end{bmatrix} ++ \begin{bmatrix} 0 & 0 & 0 & 0 \\ 1 & 1 & 1 & 1 \end{bmatrix} += \begin{bmatrix} 1 & 2 & 6 & 9 \\ 4 & 2 & 8 & 3 \end{bmatrix}. +\f] +The operators <tt>-=</tt>, <tt>+</tt> and <tt>-</tt> can also be used column-wise and row-wise. On arrays, we +can also use the operators <tt>*=</tt>, <tt>/=</tt>, <tt>*</tt> and <tt>/</tt> to perform coefficient-wise +multiplication and division column-wise or row-wise. These operators are not available on matrices because it +is not clear what they would do. If you want multiply column 0 of a matrix \c mat with \c v(0), column 1 with +\c v(1), and so on, then use <tt>mat = mat * v.asDiagonal()</tt>. + It is important to point out that the vector to be added column-wise or row-wise must be of type Vector, and cannot be a Matrix. If this is not met then you will get compile-time error. This also means that broadcasting operations can only be applied with an object of type Vector, when operating with Matrix. -The same applies for the Array class, where the equivalent for VectorXf is ArrayXf. +The same applies for the Array class, where the equivalent for VectorXf is ArrayXf. As always, you should +not mix arrays and matrices in the same expression. -Therefore, to perform the same operation row-wise we can do: +To perform the same operation row-wise we can do: <table class="example"> <tr><th>Example:</th><th>Output:</th></tr> |