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| author | Stanislaw Halik <sthalik@misaki.pl> | 2019-03-03 21:09:10 +0100 |
|---|---|---|
| committer | Stanislaw Halik <sthalik@misaki.pl> | 2019-03-03 21:10:13 +0100 |
| commit | f0238cfb6997c4acfc2bd200de7295f3fa36968f (patch) | |
| tree | b215183760e4f615b9c1dabc1f116383b72a1b55 /eigen/doc/TutorialBlockOperations.dox | |
| parent | 543edd372a5193d04b3de9f23c176ab439e51b31 (diff) | |
don't index Eigen
Diffstat (limited to 'eigen/doc/TutorialBlockOperations.dox')
| -rw-r--r-- | eigen/doc/TutorialBlockOperations.dox | 228 |
1 files changed, 0 insertions, 228 deletions
diff --git a/eigen/doc/TutorialBlockOperations.dox b/eigen/doc/TutorialBlockOperations.dox deleted file mode 100644 index a2d8c97..0000000 --- a/eigen/doc/TutorialBlockOperations.dox +++ /dev/null @@ -1,228 +0,0 @@ -namespace Eigen { - -/** \eigenManualPage TutorialBlockOperations Block operations - -This page explains the essentials of block operations. -A block is a rectangular part of a matrix or array. Blocks expressions can be used both -as rvalues and as lvalues. As usual with Eigen expressions, this abstraction has zero runtime cost -provided that you let your compiler optimize. - -\eigenAutoToc - -\section TutorialBlockOperationsUsing Using block operations - -The most general block operation in Eigen is called \link DenseBase::block() .block() \endlink. -There are two versions, whose syntax is as follows: - -<table class="manual"> -<tr><th>\b %Block \b operation</td> -<th>Version constructing a \n dynamic-size block expression</th> -<th>Version constructing a \n fixed-size block expression</th></tr> -<tr><td>%Block of size <tt>(p,q)</tt>, starting at <tt>(i,j)</tt></td> - <td>\code -matrix.block(i,j,p,q);\endcode </td> - <td>\code -matrix.block<p,q>(i,j);\endcode </td> -</tr> -</table> - -As always in Eigen, indices start at 0. - -Both versions can be used on fixed-size and dynamic-size matrices and arrays. -These two expressions are semantically equivalent. -The only difference is that the fixed-size version will typically give you faster code if the block size is small, -but requires this size to be known at compile time. - -The following program uses the dynamic-size and fixed-size versions to print the values of several blocks inside a -matrix. - -<table class="example"> -<tr><th>Example:</th><th>Output:</th></tr> -<tr><td> -\include Tutorial_BlockOperations_print_block.cpp -</td> -<td> -\verbinclude Tutorial_BlockOperations_print_block.out -</td></tr></table> - -In the above example the \link DenseBase::block() .block() \endlink function was employed as a \em rvalue, i.e. -it was only read from. However, blocks can also be used as \em lvalues, meaning that you can assign to a block. - -This is illustrated in the following example. This example also demonstrates blocks in arrays, which works exactly like the above-demonstrated blocks in matrices. - -<table class="example"> -<tr><th>Example:</th><th>Output:</th></tr> -<tr><td> -\include Tutorial_BlockOperations_block_assignment.cpp -</td> -<td> -\verbinclude Tutorial_BlockOperations_block_assignment.out -</td></tr></table> - -While the \link DenseBase::block() .block() \endlink method can be used for any block operation, there are -other methods for special cases, providing more specialized API and/or better performance. On the topic of performance, all what -matters is that you give Eigen as much information as possible at compile time. For example, if your block is a single whole column in a matrix, -using the specialized \link DenseBase::col() .col() \endlink function described below lets Eigen know that, which can give it optimization opportunities. - -The rest of this page describes these specialized methods. - -\section TutorialBlockOperationsSyntaxColumnRows Columns and rows - -Individual columns and rows are special cases of blocks. Eigen provides methods to easily address them: -\link DenseBase::col() .col() \endlink and \link DenseBase::row() .row()\endlink. - -<table class="manual"> -<tr><th>%Block operation</th> -<th>Method</th> -<tr><td>i<sup>th</sup> row - \link DenseBase::row() * \endlink</td> - <td>\code -matrix.row(i);\endcode </td> -</tr> -<tr><td>j<sup>th</sup> column - \link DenseBase::col() * \endlink</td> - <td>\code -matrix.col(j);\endcode </td> -</tr> -</table> - -The argument for \p col() and \p row() is the index of the column or row to be accessed. As always in Eigen, indices start at 0. - -<table class="example"> -<tr><th>Example:</th><th>Output:</th></tr> -<tr><td> -\include Tutorial_BlockOperations_colrow.cpp -</td> -<td> -\verbinclude Tutorial_BlockOperations_colrow.out -</td></tr></table> - -That example also demonstrates that block expressions (here columns) can be used in arithmetic like any other expression. - - -\section TutorialBlockOperationsSyntaxCorners Corner-related operations - -Eigen also provides special methods for blocks that are flushed against one of the corners or sides of a -matrix or array. For instance, \link DenseBase::topLeftCorner() .topLeftCorner() \endlink can be used to refer -to a block in the top-left corner of a matrix. - -The different possibilities are summarized in the following table: - -<table class="manual"> -<tr><th>%Block \b operation</td> -<th>Version constructing a \n dynamic-size block expression</th> -<th>Version constructing a \n fixed-size block expression</th></tr> -<tr><td>Top-left p by q block \link DenseBase::topLeftCorner() * \endlink</td> - <td>\code -matrix.topLeftCorner(p,q);\endcode </td> - <td>\code -matrix.topLeftCorner<p,q>();\endcode </td> -</tr> -<tr><td>Bottom-left p by q block - \link DenseBase::bottomLeftCorner() * \endlink</td> - <td>\code -matrix.bottomLeftCorner(p,q);\endcode </td> - <td>\code -matrix.bottomLeftCorner<p,q>();\endcode </td> -</tr> -<tr><td>Top-right p by q block - \link DenseBase::topRightCorner() * \endlink</td> - <td>\code -matrix.topRightCorner(p,q);\endcode </td> - <td>\code -matrix.topRightCorner<p,q>();\endcode </td> -</tr> -<tr><td>Bottom-right p by q block - \link DenseBase::bottomRightCorner() * \endlink</td> - <td>\code -matrix.bottomRightCorner(p,q);\endcode </td> - <td>\code -matrix.bottomRightCorner<p,q>();\endcode </td> -</tr> -<tr><td>%Block containing the first q rows - \link DenseBase::topRows() * \endlink</td> - <td>\code -matrix.topRows(q);\endcode </td> - <td>\code -matrix.topRows<q>();\endcode </td> -</tr> -<tr><td>%Block containing the last q rows - \link DenseBase::bottomRows() * \endlink</td> - <td>\code -matrix.bottomRows(q);\endcode </td> - <td>\code -matrix.bottomRows<q>();\endcode </td> -</tr> -<tr><td>%Block containing the first p columns - \link DenseBase::leftCols() * \endlink</td> - <td>\code -matrix.leftCols(p);\endcode </td> - <td>\code -matrix.leftCols<p>();\endcode </td> -</tr> -<tr><td>%Block containing the last q columns - \link DenseBase::rightCols() * \endlink</td> - <td>\code -matrix.rightCols(q);\endcode </td> - <td>\code -matrix.rightCols<q>();\endcode </td> -</tr> -</table> - -Here is a simple example illustrating the use of the operations presented above: - -<table class="example"> -<tr><th>Example:</th><th>Output:</th></tr> -<tr><td> -\include Tutorial_BlockOperations_corner.cpp -</td> -<td> -\verbinclude Tutorial_BlockOperations_corner.out -</td></tr></table> - - -\section TutorialBlockOperationsSyntaxVectors Block operations for vectors - -Eigen also provides a set of block operations designed specifically for the special case of vectors and one-dimensional arrays: - -<table class="manual"> -<tr><th> %Block operation</th> -<th>Version constructing a \n dynamic-size block expression</th> -<th>Version constructing a \n fixed-size block expression</th></tr> -<tr><td>%Block containing the first \p n elements - \link DenseBase::head() * \endlink</td> - <td>\code -vector.head(n);\endcode </td> - <td>\code -vector.head<n>();\endcode </td> -</tr> -<tr><td>%Block containing the last \p n elements - \link DenseBase::tail() * \endlink</td> - <td>\code -vector.tail(n);\endcode </td> - <td>\code -vector.tail<n>();\endcode </td> -</tr> -<tr><td>%Block containing \p n elements, starting at position \p i - \link DenseBase::segment() * \endlink</td> - <td>\code -vector.segment(i,n);\endcode </td> - <td>\code -vector.segment<n>(i);\endcode </td> -</tr> -</table> - - -An example is presented below: -<table class="example"> -<tr><th>Example:</th><th>Output:</th></tr> -<tr><td> -\include Tutorial_BlockOperations_vector.cpp -</td> -<td> -\verbinclude Tutorial_BlockOperations_vector.out -</td></tr></table> - -*/ - -} |
